WILD FLOWERS
AND TREES | |
OF COLORADO

RAMALEY

Sir his

ild flowers and trees of Colorado.

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WILD FLOWERS
AND TREES OF
COLORADO

By
Francis Ramaley, Ph.D.

Professor in the University
of Colorado

Boulder, Colorado
A. A. Greenman, University Book Store
1909

en
eee,

RITW

A. 222447 .

Copyright 1909
By Francis Ramaley

PREFACE

This little volume is intended as an introduction to Colorado plants.
It is not the result of book study but of many summers’ work in forest
and meadow, on alpine height and level plain.

The first part of the book is a short essay on the plants of Colorado—
their habits, distribution and relation to altitude. In the short compass
of the book it is possible to describe only a few of the flowering plants
of the state but the examples chosen are of the most interesting species
from different altitudes.

’ Trees, the author believes, are the best plants to begin with in a
study of vegetation. Hence, he has given, in addition to drawings of
many of the species, rather full accounts of some of the more important
ones. Keys are arranged for the determination ofall native trees of
the state. By the use of these it becomes possible to recognize with
ease the different species met in a.mountain journey or during a trip on
the plains.

BouLpDER, CoLo.
March, 1909

COLORADO WILD FLOWERS”

PLANTS AND THEIR DISTRIBUTION

There are more different species of wild flowering plants in Colorado
than in any state of the Union except California, the number thus far
recognized being about 3,000. It is largely because of the varied con-
ditions of climate that so many plants are able to grow within the borders
of the state. A single small area, such as Boulder County, has more
different climates than could be found in a whole state such as Pennsyl-
vania or Illinois.

Besides the climatic differences, which are chiefly the result of altitude,
an important feature which makes Colorado so rich in plant forms
is its central location. Passing through the state is the continental
divide which is the westward limit of extension for eastern plants, and
the eastern boundary for western plants. Botanically speaking the
state may be said to lie half way between the Atlantic and Pacific,
although geographically it is somewhat nearer the Pacific.

In the western half of the state the plants are such as occur also in
Utah, Idaho and Nevada, while on-the plains to the east of the continental
divide the plants are related to those of Nebraska and Kansas. The
flora of the higher mountains is much the same on the two sides of the
divide.

Probably the easiest way to gain an idea of the Colorado flora is to
consider in order some of the conditions under which plants grow. The
simplest classification is made according to altitude. Changes in altitude
mean differences in climate and, because of this, differences in the trees
and herbs. It is possible to recognize a series of zones or belts of vegeta-

« There is no popular work of any kind dealing with Colorado plants. The author has in preparation
an extended work, which may prove useful. Only one technical book of wide scope has been pub-
lished in recent years, viz., RyDBERG’s Flora of Colorado, which may be obtained from the Director of the
Experiment Station, Colorado Agricultural College, Ft. Collins. Professor Aven Nelson, of the University
of Wyoming, will soon have ready a manual of Rocky Mountain Botany.

T

CONTENTS

PAGE

PREFACE : or ey wae “AE x & oN
CoLoRADO WILD’FLOWERS . b. Be pe ie ct wine do ME
Forest FORMATIONS AND Forest TREES . i (8. @ J 2°37
Key TO THE GENERA OF EVERGREEN TREES : : ‘ 51
KEY TO THE GENERA OF DeEcIDUOUS TREES Be es ug. G2
DESCRIPTIONS AND Krys To SPECIES. . Yn cb ttle 2 4558
BIBLIOGRAPHY OF ARTICLES DEALING wITH COLORADO TREES 75

INDEX OF FLOWERS AND TREES . : ae 7

vii

Fic. 1—Sanp Lity (Leucocrinum montanum)

Abundant on the plains in early spring; occurs sparingly in the foothill and montane
zone. The delicate white flowers resemble somewhat those of Narcissus. (Two-thirds
natural size.)

COLORADO WILD FLOWERS 3

tion which, extending from the lower altitudes to the highest points, are

as follows:

1. Plains zone—treeless, except along streams, dry in summer but with
a profusion of handsome flowers in the moist months of spring.

2. Foothill zone—scattered trees; rock pines, pinyons, oaks, etc. The
flowering herbs are numerous and remain in blossom longer than do
those of the plains. The climate resembles that of Iowa and northern
Illinois but is drier.

Fic. 2.—A Group or SAND LILIES

3. Montane zone—chiefly forests of lodgepole pine or, in southern Colo-
rado, Douglas spruce, white fir and some rock pines; aspens are
abundant. Here are many beautiful flowering plants which do not
extend down to the lower altitudes of plains and foothills. The
climate resembles that of New England but winters are more mild.

4. Sub-alpine zone—chiefly forests of Engelmann spruce. The flower-
ing herbs are not so numerous as in the lower zones but are very

4 WILD FLOWERS AND TREES OF COLORADO

Fic. 3.—GULLIES AND BLUFFS OF THE PLaIns REGION

It is only in the spring that any number of wild flowers can bé found here. The
summer months are hot and dry.

Fic. 4.—Lrvet AREA IN THE PLAINS REGION

Grasses and flowering herbs form a conspicuous vegetation-cover in spring.

COLORADO WILD FLOWERS 5

handsome. There are many lakes and ponds. The climate resembles
that of Hudson’s Bay.

5. Alpine zone—above the limit of tree growth. Flowering herbs are
numerous; those in drier situations are small and matted with a pro-

Fic. 5.—PrRickKLy Poppy (Argemone intermedia)

A tall, coarse plant with large white flowers and a sticky, yellow juice. Common
along roadsides and railway tracks of the plains region, seldom extending any distance
into the foothills. (One-sixth natural size.)

fusion of brightly-colored flowers. The climate is very cold, summers

are short and winters long.

In each of the zones named above it is possible to recognize a great
many special kinds of plant formation depending on soil-moisture, shade

6 WILD FLOWERS AND TREES OF COLORADO

and other factors. Thus the flowering plants of a moist, shaded gulch
are not the same as those of a dry, sunny ridge even at the same altitude,
and great differences are seen between the plants which fringe an irrigat-
ing ditch and those that border a dry country road.

The limits of the present account will not permit a discussion of the

Fic. 6.—VIEW ON THE PLATTE RIVER NEAR GREELEY, COLO.

A narrow belt of forest extends along the river bank. The principal trees are broad-
leaf cottonwoods, box-elders and alders.

plants of all the different locations. It will only be- possible to call
attention to a few of the most interesting facts in regard to the relation
between altitude and plant life and to show by the use of illustrations
some of the more striking or notable flowering herbs of the different
plant zones.

COLORADO WILD FLOWERS 7

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Fic. 7.—EvENING Primrose (Pachylophus caespitosus)
There are many different kinds of evening primroses in Colorado, most of them

“ occurring on ‘the plains but some extending to the foothills. They often fill up abandoned

fields after the manner of dandelions, blooming profusely in late spring or early summer.
This particular species has pink flowers, but some kinds are a deep yellow and others are
white. (One-half natural size.)

8 WILD FLOWERS AND TREES OF COLORADO

ALTITUDE, CLIMATE AND PLANT LIFE

Plants of spring and autumn are very different. Early in the year
many species come into blossom which require some considerable

Fic. 8.—BROADLEAF COTTONWOODS ALONG A SMALL CREEK

This is a common type of scene on the great plains of eastern Colorado. Water courses -
may be recognized miles away by the presence of straggling cottonwoods.

amount of moisture. The later-blooming flowers are those which are
able to withstand dryness. After June there is very little rain in the
plains region so that the ground becomes parched and dry. Usually in

COLORADO WILD FLOWERS 9

(oS
Fic. 9.—Pasque FLOWER (Pulsatilla hirsutissima)

A spring-blooming plant very common in the foothills and sparingly distributed in the
montane and higher zones. The flowers are light blue or lavender in color with a woolly
circle of bracts on the flower stalk. The leaves appear after the flowers have faded. In
‘Colorado this plant is frequently called ‘Anemone.’ (One-half natural size.)

“10 WILD FLOWERS AND TREES OF COLORADO

autumn there are few species in blossom except such coarse plants as
sunflowers and their relatives. -

In mountain districts there are showers throughout the summer and
_ so there is a continuous succession of flowers. Many of the plants which
belong more properly to the montane zone occur also in the foothills

Fic. 10.—PAsQque FLOWERS (‘‘ANEMONES”’)

where they first come into blossom. A week or two later they are in full
bloom in their proper habitat. A few weeks later than this, with the
general warming up of the summer a few specimens may be found in the
sub-alpine districts. z

Unless the differences in climate which may be recognized at
different altitudes are constantly kept in mind it is impossible to under-
stand the flora of amountain region. With each thousand feet additional

COLORADO WILD FLOWERS II

altitude there is a loweting of temperature to the extent of about three
degrees Fahrenheit so that if the people in Denver are fanning them-
selves and trying to keep cool in a temperature of eighty in the shade, the
camper or fisherman up at Tolland will find it cool and pleasant for
strenuous exercise, since he is 4,000 feet higher and is enjoying a tempera-

Fic. 11.—MESAS NEAR BOULDER, COLO.

The mesas are flat-topped hills which extend out, peninsula-like, to the plains. Next
to the mountains the mesas are covered with pines while toward the plains they are as
treeless as the plains themselves.

ture of sixty-eight. This difference of temperature has its effect on the
plant population. Indeed there are very few wild plants at Denver
_ which also grow wild at such an altitude as that of Tolland.
Differences observed in regard to plants of the mountains which
distinguish them from the plains species are generally ascribed to “alti-

12 WILD FLOWERS AND TREES OF COLORADO

tude” in a very loose way. It is worth while finding out what this .
really means. To most people thinness of the air is the first thing thought
about in connection with high mountain districts. It makes breathing
difficult and a person is soon “winded” by slight exertion. But this.

Fic. 12.—VEGETATION OF THE MESAS

The view shows the western part of two mesas next the foothills. Pine trees form
an open forest on the top of the mesa while the sides are bare. In the gulch there are
thickets of willow and thornapple. .

thin air does not disturb plants. Indeed there have been experiments’
made upon plants in laboratories which show that they grow very well
in glass cases when a part of the air is removed and make a larger and
faster growth than when under ordinary conditions. Hence, it is apparent
that the dwarfing of high-altitude plants is not due to rarity of atmosphere.

COLORADO WILD FLOWERS 13

As is well known, plants reach greatest luxuriance in the tropics
where, in addition to high temperature, there are to be found wet soil
and damp atmosphere. On mountain summits of the Rockies the
opposite conditions prevail. The air temperature is low every night
in the year. Rainfall is not great. The soil is never warmed except
for a few inches at the top. This cold soil makes the roots sluggish

Fic. 13.—Rock RipcE CouNTRY OF NORTHERN COLORADO

In this part of the foothill region the valleys have a dense covering of long grass
while the ridges support shrubs of mountain mahogany and scattered pines.

in their work and they cannot absorb. much moisture. Hence, even
though there be plenty of moisture in the ground the soil may be-con-
sidered “dry” with reference to plants. They cannot make use of the
water which is present_in the, soil.

In addition to the inability of roots to absorb moisture there must
be considered the high winds which rapidly dry out vegetation and the

14 WILD FLOWERS AND TREES OF COLORADO

intense light of the noon-day sun which shines through so little atmosphere
that it is very bright indeed. As a result of these various unfavorable
conditions the mountain tops are able to support only a very sparse
growth of plants. .

Dryness of soil, intense light, high winds, low temperatures and short
summers are all unfavorable to tall growth of plants. But the author

Fic. 14.—A BROAD VALLEY IN THE Rock RiIpGE COUNTRY

Foldings are seen in the geological strata across the valley. In the foreground are
cottonwoods and various deciduous trees and shrubs.

believes that these are not really the cause of the dwarf habit of alpine
plants. Alpine plants are plants which have naturally a low, matted
form and are therefore able to grow under the severe conditions of the
alpine climate. Any other kind would be killed. There are many low,
matted plants which grow on the dry plains, too, and on the bare rock
ridges of northern Colorado. , :

It is perfectly natural that there should be a difference in the plants

COLORADO WILD FLOWERS 15

Fic. 15.—SULPHUR FLOWER (Eriogonum umbellatum)

This is a somewhat woolly plant with dense clusters of small sulphur-yellow flowers.
The plant here figured belongs chiefly to the foothills, but other species occur at high
altitudes, notably one with straw-colored flowers. (One-half natural size.)

16 WILD FLOWERS AND TREES OF COLORADO

of low and high altitudes. Just as the plants of Louisiana are unlike
those of the Hudson’s Bay country so we must expect the plants of
the plains to be different from those of the high mountains. The
climates are as different in the two cases.

If a person sees a sulphur flower on the plains at Denver and then

Fic. 16.—CANYON VEGETATION

This steep-walled canyon is in the sedimentary rock area of the foothills. At the
left are willows and narrowleaf cottonwoods; to the right on the sloping canyon-sides are
junipers and cedars. Douglas spruces and rock pines are seen in the background.

sees another plant with somewhat similar flowers on the top of Mt.
McClellan he may think that the two are merely forms of the same
species altered by the conditions. But this is not the case. They are
just as much separate things as are the polar bear and the common brown
bears of the temperate zone; just as different as the negro of Africa

: COLORADO WILD FLOWERS 17

and the white man of Europe. It is not the climate which makes the
negro black, the Chinaman yellow and the European white. It is their
inner nature. Moved from one continent to another they remain the
same color that they were in their former home. So it is, for the most
part, with plants.

In most cases when the dwarf, matted species of the alpine heights

Fic. 17.—OPEN FooTHILL FOREST

This is a typical scene in the foothill zone; rock pines on the ridges with willows and
alders by the stream bank. ;

are transplanted to lower altitudes and there cultivated they do not change
much in form. Many of them refuse to grow in the changed condi-
tions. A few only become modified to any extent.

The principal effect of altitude is to limit the geographical extension
of plants by changing the climate. The plants which make their home
on the tops of mountains are much like those of the arctic regions. They

18 WILD FLOWERS AND TREES OF COLORADO

Fic. 18.—MovuNTAIN PARK IN THE FOOTHILLS

Fic. 19.—FossiL STUMP AT FLORISSANT, COLO.

This is all that is left of one of the “big trees” which grew in Colorado in former
geologic ages. At present the ‘“‘big trees” grow only in California.

COLORADO WILD: FLOWERS 1g

grow in these places because they, and they alone, are able to withstand
the.very unfavorable conditions. We must not think that the alpine
climate makes the forget-me-not or the mountain campion small. These

Fic. 20.—CANYON SCENE IN NORTHERN COLORADO

Douglas spruces occupy the shaded slopes while cottonwoods and willows occur in
the lower part of the canyon near the water.

plants are naturally small. They are of such a nature that they can get
along in dry soil and are not injured by cold. Hence they grow in
places where these conditions exist.

20 WILD FLOWERS AND TREES OF COLORADO

There is no good reason for thinking that plants develop useful per-
manent structures in response to climate. If useful changes in plant
structure become developed by chance variation or otherwise it is likely
that the plants thus modified will survive and perpetuate their kind.
So, in the course of long ages, plants of a region will appear to have

Fic. 21.—Park LANDSCAPE IN THE MONTANE REGION

The view is taken at Tolland on the Moffat Road and shows part of South Boulder
Park with its winding, willow-fringed creek flanked by meadow land.’ Park Lake is at
the left. :

adapted themselves to particular surroundings. Altitude, with its
accompanying differences in climate, does not change plants—it merely
determines where any particular species will grow.

There are certain other popular misconceptions about plants of
Colorado which may be considered briefly. It is a common idea that

Fic. 22.—MovuntTaIn Daisy (Erigeron macranthus)

This handsome flower is common in the montane and adjacent zones. Many species
of Erigeron are found in Colorado; all look much alike in general appearance but there
are differences in the leaves and in the color of the flowers. This particular plant has
purplish-pink ray flowers and a yellow center. (One-half natural size.)

22 WILD FLOWERS AND TREES OF COLORADO

Fic. 23.—BLUE CoLUMBINE (Aquilegia coerulea)

Everyone knows the Colorado state flower. It grows chiefly in the montane and
sub-alpine zones. A yellow columbine occurs in southern Colorado and a red-and-yellow
species on the western slope. (One-half natural size.)

COLORADO WILD FLOWERS 23

Fic. 24.—A SUB-ALPINE FOREST.

This illustration shows the large size of some of the Engelmann spruces. A snow
bank in the foreground is nearly covered up with pine and spruce needles. The small
building is a shelter for thermometer and other instruments used by the author in some
investigations made in the summer of 1908.

24 WILD FLOWERS AND TREES OF COLORADO

because of the altitude or climate there are no bright autumnal colors.
There is, however, no foundation for this belief. The poison ivy, the
grape, the Virginia creeper are quite as brilliant in the Rocky Mountains
as elsewhere. The aspens turn to bright gold in autumn and the hills
and canyon sides are aflame with crimson sumacs. It is true that in
the cities one may miss the brilliant reds of the hard maple or scarlet
oak, for these trees are seldom planted, but there are instead the yellow
cottonwoods, locusts and soft maples. Wherever sugar maples and
oaks are planted they assume just as beautiful autumn tints as in their
native homes.

Another mistaken idea is that Rocky Mountain flowers have no
odor. Some flowers here, as elsewhere, are scentless, but certainly not
all, nor most all, differ in this respect from plants elsewhere.

The interest which attaches to the wild flowers and trees of Colorado
is due to their great variety and to the unusual beauty of many of the
individual species. These are not the result of altitude or climate. The
great differences in altitude of different parts of the state permit the
growth of an unusual number of species and many of these are quite
different from those with which the tourist or the settler has been familiar
in his eastern home. But plants behave in Colorado much as they do
elsewhere in the world. A mountain district is not so different from
other regions except in the wonderfully varied conditions which are
presented for plant growth.

PLANTS OF THE GREAT PLAINS

We sometimes think of the plains as flat expanses, dull and devoid of
interest. Yet, for the most part, there is not absolute flatness. Well-
drained, gently sloping areas alternate with steep gulches cut by storm
waters. There is not, however, that rolling character of the country
which belongs to the central and eastern states and which is the result
of the action of glaciers of the great ice age. It is easy to see that the
great plains represent an entirely different geological formation. Indeed
they were sea-bottom in not such very remote geological times and their
fine-grained soil is the deposit of silt from ancient rivers. But in the
centuries since these deposits were laid down and since the ocean-floor

COLORADO WILD FLOWERS 25

Fic. 25.—SUB-ALPINE LAKE SCENE

Scattered lily pads are shown floating on the water; sedges occupy the lake edge;
these are followed by willows and birches; finally there are the Engelmann spruces of the
forest. The pond lilies of Colorado have large yellow flowers. The species is Nymphaea
polysepala.

26 WILD FLOWERS AND TREES OF COLORADO

Fic. 26.—BEARD TONGUE (Pentstemon alpinus) -

Colorado is famous for its Pentstemons of which there are fully thirty different kinds
in the state. Most of them have blue or lilac flowers although a few are scarlet. The
species here figured is very common in late summer in the sub-alpine zone. The flowers
are a deep, rich blue. (One-half natural size.)

COLORADO WILD FLOWERS 27

Fic. 27.—RED ORPINE (Clementsia rhodantha)

One of the most interesting sub-alpine plants is here figured. It has fleshy stem
and leaves and dark red flowers. The plants grow along streams and in marshy places.
When found in dry soil they are small and dwarfed, having the appearance of alpine plants,
well shown by the smaller specimen in the drawing. The dwarfing is due to dryness,
not to altitude (i. c., cold climate), as is shown by the fact that both the ordinary form and
the ‘“‘alpine form” may occur at the same altitude. The name Clementsia was given to
this plant in honor of Professor Frederic E. Clements, a distinguished botanist who has
made important studies in Colorado.

28 : WILD FLOWERS AND TREES OF COLORADO

was raised high and dry above the water level, the storm waters from
thunder showers and the spring freshets of mountain streams have
worn away the land unevenly into valleys, gulches and plateaus.

Even where there has been little cutting away by stream erosion,
where the plain ‘is truly a flat expanse, it is interesting and beautiful

Fic. 28.—SHRUBS AND TREES NEAR A SUB-ALPINE LAKE

To the left are shrubby willows and birches; at the right are wind-blown Engelmann
spruces. It is to.be noted that there are no branches on the side of the trees next to the
lake. This is due to the prevailing winds which are from that direction.

at least in the joyous spring season. At that time there are days and
days with short showers or steady drizzling rain and the dry barren soil
becomes moist and fertile. For many of the plains plants the growing
season thus ushered in is very short, confined to April, May and June.
This is because of the dryness which belongs to summer. So a whole
series of profusely-flowering herbs come to blossom in quick succession,

COLORADO WILD FLOWERS 29

finish their growth and mature their seeds before the hot, dry months
of July and August.

The limits of the present discussion do not permit any detailed account
of these plants. Only three examples are chosen for illustration, the
sand lily, prickly poppy and evening primrose, while at least fifty hand-

Fic. 29.—SNow DRIFTs IN A SUB-ALPINE FOREST

These large drifts are located north-east of a ridge which serves as a protection from
the heat of the sun. Many large drifts remain in the shelter of ridges or under trees well
into June and July.

‘some and abundant flowers could be named. But it is worth while to
call attention to the beauty of springtime on the plains so that those who
can may make the most of this beauty. In addition to sand lilies and
evening primroses there are milk vetches, multi-colored loco weeds
and the brilliant yellow buck beans (Thermopsis). Grotesque prickly
pears and other cactuses, so abundant in many places, take on a brighter

30 WILD FLOWERS AND TREES OF COLORADO

green in early spring and their handsome flowers, some yellow, some
red, add much to the beauty of springtime scenes. The Spanish bayonet
in blossom is something not soon forgotten, its usefulness for decorative —
purposes being shown on the title-page of this book. __

In speaking of the plants of the plains it will not do to forget the sage
brush. What is called sage brush is very different from what house-

Fic. 30.—SuB-ALPINE LaKE SHORE.

The sedges and grasses in their growth encroach upon the water and will eventually
fill up the lake converting it into a meadow.

wives use to flavor their Thanksgiving turkey. There is a little of the
same odor but at this point the resemblance stops. Many of the plants
are not large, being only a few inches high. Others have a distinctly
bushy form and grow about three or four feet tall. The whitish green
of the leaves and stems gives impress to the landscape. Some prosaic
people do not like it. They say that it gives an air of barrenness to the

COLORADO WILD FLOWERS

>,

Op ck

G
ma:

Fic. 31.—LittLe Rep ELEepHant (Elephaniella groenlandica)

A common plant of sub-alpine bogs or marshy ground along streams and around
lakes. The flowers are dark red or crimson.

(Two-thirds natural size.)

31

32 WILD FLOWERS AND TREES OF COLORADO

Fic. 32.—HAREBELL (Campanula petiolata)

This handsome blue-flowered plant is common in the moist parts of the alpine zone .
in late summer. It also grows in the other life zones down to the foothills. (Two-thirds
natural size.)

COLORADO WILD FLOWERS 33

view; but, even so, the nature-lover enjoys it. Something of the artistic
temper seems needed for an appreciation of the beauty of this soft green.
There is none of the vividness which means fulness of life—that is seen
in the grasses of early spring—but there is a charm in the delicate-colored
landscape of midsummer with its dull brown of dead grass stems and
the soft gray of sage brush.

MounTAIN Parks

It is quite out of the question to close this very short account of
Colorado wild flowers without some mention of mountain parks. The
author has in mind Estes Park, South Boulder Park and some of the
valleys in Platte Canyon. A mountain park may be defined as a level
area in the foothill or montane district surrounded by hills and mountains.
Some of the parks are a few acres in extent, some are many square miles.
Botanically they may be considered as enclosed prairies shut off from
other prairies by high hills and communicating with the lowlands by
means of a river gorge through which flows a mountain stream. Along
the course of the stream there is usually a broad area with rich soil and
plenty of seepage water where luxuriant vegetation develops.

Colorado belongs to the “great dry country” and there are few places
in the state which offer views of green meadows and winding streams.
But the meadows of the mountain parks are most beautifully green.
Even to late summer and autumn the color continues and there is a
sharp contrast with the dull gray and brown of hillsides or the whiteness
of distant snowfields on the alpine peaks.

When we climb out of the park up the side of one of the surrounding
foothills and look below us we see broad level sunlit reaches, shallow
valleys and rolling hills. Beyond all this, across the park, are the
foothills which shut it in on the other side. The creek may be seen as a
silvery thread which winds along toward the canyon which is the outlet
to the park.

There can be no adequate written description of a mountain park.
When the topography is described and when all the trees and grasses
and flowering herbs are named there are still the delicious mountain air
and the pure sunlight. These are forever unknown to one who lives”

Fic. 33.—RyDBERGIA (Rydbergia grandiflora)

This beautiful plant is named in honor of Dr. Per Axel Rydberg, the distinguished
author of the Flora of Colorado. It is one of the most striking plants of the alpine zone,
being common in moister places in early summer. The ray flowers are a handsome
yellow and the center orange-brown. (Two-thirds natural size.)

COLORADO WILD FLOWERS 35

_ Fic. 34.—FoRGET-ME-Not (Eritrichium argentium)

A small, low, matted plant able to endure the extreme cold of the alpine7climate.
The flowers are a pure blue. (Natural size.)

Fic. 35.—Movunrain Campion (Silene acaulis)

A typical matted plant of drier places in the alpine zone. It is well adapted to the
severe climate.

36 WILD FLOWERS AND TREES OF COLORADO

his life east of the great plains. Day after day the sun comes up unclouded
over the eastern hills and shines resplendent from the great blue sky.
Without moisture or dust in the air the blueness is intense. The trees
cast black shadows on the ground beneath. There is no blending of
colors in the landscape. Everything stands out boldly. No haze
obstructs the view. In the afternoon a shower comes up with thick
black clouds rolling into ominous mountain masses—a few drops of
rain, perhaps distant thunder, and again the bright azure sky.

So the charm of the mountain park to the nature-lover comes not
only in the gullies and ridges, in the wild flowers and trees, but also in
the light and shadow, which, ever changing, fill the landscape with
interest. The matter-of-fact man may say that a pine tree is just a
pine tree; but he who studies just one single pine tree knows that it is
not always the same. With the times of day the shadows change and
each separate hour gives new objective sensations which change our
inner feelings of the world about us. The charm of the mountain park
is in the green waving meadows, pine barrens and quaking aspens, loco
and sage brush—and everything more beautiful and full of interest
because of the tonic air and brilliant sunshine.

FOREST FORMATIONS AND FOREST TREES

The study of trees.—Anyone who wishes some acquaintance with
plants may well begin with a study of trees. For such study only a very
little technical knowledge is required, while to learn much about “wild
flowers” or grasses or ferns it is necessary to master a great many special
terms. The trees in Colorado are so few that it is possible in a single
season to become well acquainted with most of the different kinds in
any particular locality. Hence the student who is looking for rapid
results may well begin any outdoor botanical work with a study of
trees. ?

Scientific names.—Every plant known to science, whether a tree,
shrub or herb, has what is known as a scientific name. Thus Populus
alba is the white poplar, Populus nigra the black poplar, etc. In each case
Populus is the generic name. The particular kind of poplar is indicated
by the specific name. So all oaks are known as Quercus, all elms as
Ulmus, etc. As a rule botanists agree on these scientific names which
are the same in all countries, of the world, but in some cases there is a
difference of opinion. This is well illustrated in the case of the maples
and box-elders. Acer, the ancient name for maple, is used for all of the
true maples but it is a question among botanists whether or not the box-
elder should be called Acer. Indeed, many people, disregarding the
similarity of fruits and seeds, say that box-elder is something entirely
apart and should have a different name. For this purpose the names
Negundo and Rulac have been employed. Another source of con-
fusion comes through the naming of the same species by two or more
different botanists working separately and not knowing of the work
of the others. A particular kind of tree or other plant may thus receive
two or more names and each of these names may come into use among
certain people. It is a rule that the oldest published name is to be
followed if the plant has been named in the correct genus. So it often
‘happens that a much-used name has to be discarded when the true
history of the plant becomes fully known. In technical descriptions

37

38 WILD FLOWERS AND TREES OF COLORADO

the name of the botanist who has described the plant is affixed to the
scientific name. This is done in order that anyone wishing to examine
the original description of the plant may more easily find it.

Forest formations.—It is a simple matter to classify the forests of
Colorado. They fall into two groups, those of the plains region and
those of the mountain districts. The former are of slight economic
importance at the present time but their existence suggests the possi-
bility of tree-planting which may in time become highly profitable.
River-bottom forests and pine-ridge forests occur in the plains region
to the east of the continental divide, while in the western part of the
state there are large areas with a growth of quaking aspen and of pinyon
pine which it is difficult to classify. They might be termed either pine-
ridge or foothill forests. In the mountain districts there are no trees
of importance except the “ evergreens.”

Forest formations of mountain districts.—These are composed of
coniferous trees, the various species of pine, spruce and fir and the single
species of Douglas spruce. Generally the foothills support an open
formation of rock pine’ while in the moister canyons there are Douglas
spruces.?. In southern Colorado the pinyon pine? forms a conspicuous
part of the foothill forest and in places in the southern and western parts
of the state there are some oaks of consequence. In the montane
region a closer forest exists, composed largely of lodgepole pine,* with
some Colorado blue spruces$ along the streams. The best timber, how-
ever, is in the sub-alpine spruce forests. These consist essentially of
Engelmann spruce® with some admixture of limber pine,’ sub-alpine
and white fir’ and, in places, bristle-cone pine.°

Forest formations of the plains region.—The river-bottom and
pine-ridge forests occupy essentially different habitats. Along the
water courses there is found a good growth of cottonwoods and willows
with occasional box-elders, hackberries, mountain maples and alders.
Where the stream has not cut a deep bed, and the ground slopes gently

1 Pinus scopulorum. 6 Picea engelmanni.

® Pseudotsuga mucronata. 7 Pinus flexilis.

3 Pinus edulis. 8 Abies lasiocarpa and Abies concolor.
4 Pinus murrayana. ° Pinus aristata.

8 Picea parrayana.

FOREST FORMATIONS AND FOREST TREES 39

away at the sides, these river-bottom forests may be a quarter or half-
mile in width. More often, however, they are much narrower. Along
the smaller streams there is frequently a single row of cottonwoods or
willows. The pine-ridge forests are on the high ground extending
between adjacent streams where they grow in coarse, frequently rocky
soil. Good examples of pine-ridge forests are seen along the divide
between the South Platte and the Arkansas and also at the edge of the

uNNAN )
1

ae

KP

°
'
{
1
|
1
{
ty
I
|
1
'
i}
t
'
i}
{
I
'
t
\
i
ae
1
'
ior

t
t
'
t
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'

Fic. 36.—Map oF Cotorapo. The continental divide is shown by the heavy dotted
line, the front range of foothills by the short horizontal lines. East of the foothills lie the
great plains.

“high plains” in the northeastern part of the state. The trees of these
ridges are rock pines and cedars which form scattered groups hardly to
be dignified by the name of forest. Near Pawnee Buttes in northeastern
Colorado there are limber pines instead of rock pines. To the south,
and in certain parts of the western area of the state, the pinyon pine is
added to the rock pine and cedar. -

Classification of forests.—From:a botanical standpoint forests may

40 WILD FLOWERS AND TREES OF COLORADO

be distinguished as mesophytic and xerophytic. The former are those
made up of trees requiring a moderate amount of moisture, the latter
are dry-country forests capable of enduring drought; they occur in
regions of slight rainfall or in situations where the run-off is rapid.
Mesophytic trees in Colorado are confined to areas where there is con-
siderable seepage water, except in the case of Engelmann spruces in the
sub-alpine zone where there is much more rainfall than at lower altitudes.

Tt may be convenient to list the principal forest formations of Colo-
rado in tabular form.

Name of Formation Sree ch Principal Trees
Pine-ridge Forest............ Xerophytic Plains Rock Pine
Cedar
River-bottom Forest......... Mesophytic Plains Broadleaf Cottonwoods
Willows
Foothill Forest*...........-. Xerophytic Foothill Rock Pine
Pinyon Pine
Canyon Forest............-+. Mesophytic Foothill and | Narrowleaf Cottonwood
Montane Willows
Thornapples
Plums
Cherry,
Douglas Spruce
Aspen Forest.........-.+++- Mesophytic Montane and} Quaking Aspen
Foothill
Montane Dry Forest......... Xerophytic Montane Lodgepole Pine
Rock Pine
Sub-alpine Moist Forest...... Mesophytic Sub-alpine Engelmann Spruce
Firs
Sub-alpine Dry Forest....... Xerophytic Sub-alpine Limber Pine
Lodgepole Pine
Sub-alpine Scrub “Wind
Tim bet. ocak nae toes Xerophytic Sub-alpine Engelmann Spruce
Limber Pine
Fir

* The pinyon pine is found only in the warmer and drier parts of the state. Oaks, chiefly shrubby species,
enter into the foothill forest formation in certain places. They are entirely absent from the foothills north
of Denver.

Distribution of species.—The tree flora of the state embraces fifty-
five species belonging to twenty genera. Most of the individuals, as
well as the species in general, are found in the foothill, montane and
sub-alpine zones of plant life. Timberline, at about 11,000 or 12,000

FOREST FORMATIONS AND FOREST TREES 41

feet above the sea, is the upper limit of tree growth, although some
shrubby willows occur in the alpine zone above. As noted in the preced-
ing pages, the trees of the plains are to be found only along water courses
or. on the. pine ridges of the high divides between streams. In the
following table the general distribution of each tree is stated in relation
to the continental divide, which extends north and south through the

Fic. 37.—Rock PINES

Lower limit of tree growth on mesas and foothills. Young sumacs in the fore-
ground. Late winter.

state, dividing it into nearly equal parts. It will be noticed that nearly
all of the trees occur both east and west of the divide, somewhere in their
distribution. As a matter of fact the same species does not necessarily
occur at opposite points east and west of the main range. Those oaks,
for example, which are present in the northwestern part of the state do
not cross to the foothills of the eastern slope in northern Colorado but

42 WILD FLOWERS AND TREES OF COLORADO

are found at Colorado Springs and southward. The distribution of the
pinyon pine is similar. Many of the high-altitude trees extend far north
to British Columbia and even Alaska. A considerable number
range to the Pacific coast, but only a few show a distribution far
eastward.

Fic. 38.—Rock PINE, GROWING IN THE OPEN, ESTES PARK

Limits of tree distribution. -The upper limit of tree growth, or timber-
line, is variable as to altitude. On north exposures the trees do not
extend so high up the mountain side as they do on the warmer and less
windy south slope. Cold, wind and dryness all combine to limit the
upward extension of forests on mountains. At timberline are found
scattered clumps of wind-blown trees often contorted into fantastic

FOREST FORMATIONS AND FOREST TREES 43

shapes.t At the lower limit of forest growth, on the foothills and mesas
adjoining the plains, the trees are unable to extend out to the plains
largely because of the fine soil which supports a thick covering of grasses
and does not permit trees to become started. Differences in climate
are also important. The plains have colder winters and warmer sum-
mers, than the adjacent foothills.2. In the mountain parks, which are

Fic. 39.—LIMBER PINE NEAR PAWNFE BUTTES, COLO.

This is the most eastward extension of its range.

i
certain broad valleys of the foothill and montane regions, while forests
are present on the hillsides there are only a few scattered trees on the
level ground below. This absence of trees is probably to be accounted
for by the fineness of soil and greater severity of climate.

x This subject is discussed with some completeness by Mr. W. S. Cooper in an article referred to in the
bibliography. From 11,000 to 12,000 feet may be considered the usual limit of trees.

2 A comparison of the climates of plains and. foothills is made by the present writer in the article referred
to in the bibliography: ‘‘Studies in Mesa and Foothill Vegetation.” :

Name of Tree

Relation to Con-
tinental Divide

Zone or Region of Occurrence

murrayana............
scopulorum........ ree

Picea engelmanni
parryana

Pseudotsuga mucronata.......
Abies concolor............++.
lasioearpa...........--
Sabina monosperma..........
scopulorum........-.--
utahensis...........+.-
Populus acuminata...........
angustifolia............
balsamifera............
sargentil.............-
tremuloides............
wislizeni..............
Salix amygdaloides...........
bebbiana..............
exigua......... ae Re

Betula andrewsii
fontinalis
Alnus tenuifolia.

Quercus gambellii...........
leptophylla............
niteScensS...........+..

utahensis
Celtis douglasii
FS4@. reticulata

Cercocarpus ledifolius........
Amelanchier alnifolia..... ..
Crataegus cerronis...........
coloradensis ...........
coloradoides ..........
COSI 4 ¢ sce s 4.5 seaedeccia
laurentiana....... Estes
occidentalis ...........
rivularis ..............
saligna ..........0.04-
Prunus americana............
melanocarpa...........
pennsylvanica.........
Robinia neomexicana
Acer glabrum..............0.
grandidentum..........
interior sis 642 qekeenawn es
Rhus glabra.................
Rhamnus purshiana..........
Fraxinus anomala............

East and West
East and West-
East and West
East and West
East and West
East and West
East and West «
East and West
East and West
East and West
East and West
East and West
West

East and West ( ?)
East and West
East and West
East

East and West
East and West ( ?)
East and West
East and West
East and West
East and West
East and West
East and West
East :
East and West
East and West
East and West
East and West
East and West
East and West
East ( ?) West
East and West
West

East and West
East and West
East

East

East

East

East

West

West

East

East and West
East

East and West ( ?)
East and West
East and West
East and West (?)
East and West
West

West

Montane, Sub-alpine
Foothill

Sub-alpine, Montane (Foothill)
Montane, Sub-alpine (Foothill)
Foothill, Montane
Sub-alpine, Montane
Montane, Foothill
Foothill, Montane
Montane, Foothill
Sub-alpine, Montane (Foothill)
Foothill (Plains)

Foothill, Montane, Plains
Foothill, Plains

Foothill, Plains

Foothill, Montane, Plains
Montane, Foothill

Plains, Foothill

Montane, Foothill, Sub-alpine
Plains, Foothill :

Plains, Foothill (Montane)
Foothill, Montane, Plains
Plains, Foothill (Montane)
Foothill, Plains (Montane)
Foothill, Montane
Foothill, Plains

Foothill (Montane)
Foothill, Montane
Foothill, Montane (Plains)
Foothill

Foothill

Foothill

Foothill

Foothill

Foothill, Plains

Foothill, Plains, Montane
Plains, Foothill, Montane
Foothill

Foothill

Foothill

Foothill

Foothill

Foothill

Foothill

Foothill

Foothill, Plains

Foothill, Plains, Montane
Foothill, Montane, Plains
Foothill, Plains

Foothill, Plains, Montane
Foothill, Montane

Plains, Foothill

Foothill, Plains

Foothill

Foothill, Plains

FOREST FORMATIONS AND FOREST TREES 45

Colorado forests in former geologic times.—Professor T. D. A.
Cockerell, the authority on fossil plants of the Rocky Mountains, has
recorded a large number of species of trees which formerly grew at
Florissant and at other places in Colorado. The most easily accessible
of his papers are referred to in a footnote.t It appears that the forests
of Miocene times were made up of pines, cedars, willows, cottonwoods,

r

Fic. 40.—COLORADO BLUE SPRUCE

birches, alders, oaks, hackberries, June berries, thornapples, locusts,
sumacs, maples, buckthorns and ashes, besides a number of eastern

CockERELL, T. D. A., ‘Florissant; A Miocene Pompeii,” Popular Science Monthly, Vol. LXXIV,
Pp. 112-126, 1908. ‘‘Some Results of the Florissant Expedition of 1908,’’ American Naturalist, Vol. XLII,
pp. 569-581, 1908. ‘

46 WILD FLOWERS AND TREES OF COLORADO

and southern trees which do not now exist in the state at all. Among
these others were: mulberry, soapberry, acacia, redbud and walnut.
No doubt the climate was much warmer at that time and, in the
mountains at least, more moist. The fossil imprints of many of the
leaves are very perfect and the trees can be told with considerable cer-
tainty. We may be sure that for thousands and perhaps millions of

Fic. 41.—SuB-ALTINE FOREST OF ENGLEMANN SPRUCE
1

years the pines, cottonwoods, cedars and thornapples have been an
important part of the vegetation of this part of the world.

Literature dealing with Colorado trees.—The well-known manuals
of botany of the eastern United States.such as Gray’s and Britton’s,
describe certain of the tree species of Colorado. So, also, the Rocky
Mountain Botany" by Professor John M. Coulter, issued many years

1 A new edition of this work, rewritten by Professor Aven Nelson of the University of Wyoming, is to
be issued in 1910.

FOREST FORMATIONS AND FOREST TREES 47

ago, gives descriptions of a part of the arborescent flora of the state.
Unfortunately there is no new work which gives all of the trees nor one
which discusses the forest formations. Probably the most useful single
book is the new work of Dr. Britton.t Anyone interested in the larger
aspects of forestry will find useful articles from time to time in the
National Geographic Magazine and in the magazine, Conservation.

Fic. 42.—SuB-ALPINE SCRUB AT TIMBEBLINE

This latter publication is the organ of the American Forestry Association.
The Flora of Colo ado? is valuable for the professional botanist—indeed
it is a perfect mine of information—but is rather too technical in its
treatment for the amateur. The present writer has made free use of
this work in the preparation of his account of the tree species of Colorado.

At the close of the present paper are noted some of the books and

1 Britton, N. L., North American Trees, pp. 1-894, New York, 1908.
> RypBero, P. A., Flora of Colorado, Bull. 100, Colo. Agric. Exper. Sta., pp. 1-447, Ft. Collins, 1906.

48 WILD FLOWERS AND TREES OF COLORADO

special articles which deal with Colorado trees. It is not intended as a
complete bibliography, but merely as a useful working list for reference.

Economic considerations.—The great importance of forests is now
recognized on every side and it is desirable that the people of Colorado
should know something of the trees of the state and of their value.
Perhaps the most important function of forests in mountain districts

Limber Pine Pinyon Pine Rock Pine
Fig. 43-—Pines. X#

anywhere is to conserve the water and prevent the land from washing.
But they may serve also to supply much needed timber for mining and
manufacturing purposes. In many parts of the state large areas of the
original forest have been cut and burned over so that there is now much
waste land in the foothills and in the mountains. Since this is neither
fit for mining nor agriculture it should, in time, come to be valuable for
purposes of forest growth. For the most part, reproduction in the forests

FOREST FORMATIONS AND FOREST TREES _ 49

of Colorado is rapid and all that is needful to insure the reforestation of
old lands is careful supervision and protection. It matters little from the
standpoint of the botanist or one interested in forests how this protection
is attained. It may be done either by federal or state authority. Private

Donglas Spruce Engelmann Spruce Sub-alpine Fir

Fic. 44.—-SPRUCES AND Fir. X%

supervision of forest lands elsewhere, at least, has not been successful.
Not only must illegal cutting be prohibited but fires must be. kept out.
If this is attended to the forests will take care of themselves.

The waste and desolation which come in the wake of forest destruc-
tion is well known. France has spent millions of dollars in reforestation
of mountain slopes. Spain, Greece, Turkey, northern Africa and China

*

50 WILD FLOWERS AND TREES OF COLORADO

have suffered because there was no supervision of forests. Conditions
in China have been recently described:

The ruthless destruction of the forests in northern China has brought about, or has
aided in bringing about, desolation, just as the destruction of the forests in central Asia
aided in bringing ruin to the once rich central Asian cities; just as the destruction of the
forests in northern Africa helped toward the ruin of a region that was a fertile granary in
Roman days. Short-sighted man, whether barbaric, semi-civilized, or what he may mis-
takenly regard as fully civilized, when he has destroyed the forests, has rendered certain the
ultimate destruction of the land itself... . . This is just one of those matters which it is
fatal to leave to unsupervised individual control. The forests can only be protected by the
state, by the nation, and the liberty of action of individuals must be conditioned upon what
the state or nation determines to be necessary for the common safety.t :

With the continued rise in the price of all kinds of wood the forests
of Colorado may be made one of the great economic assets of the state
in the future. They will serve for protection to the headwaters of our
streams and if rightly managed will furnish a constant supply of timber
for industrial and building purposes.

The cottonwoods of the gulches and river bottoms are, to a con-
siderable extent, made use of for fences and for other rough construction
work. If farmers and others would take pains to plant these and other
more valuable trees they would secure profitable returns. Many of the
smaller trees of the state are proving useful as shade trees and still others
are being introduced into cultivation for ornamental purposes in parks
and private grounds. The thornapples are especially promising as
ornamental trees because of both flowers and fruit, while the cotton-
woods, hackberries and box-elders are useful for shade.

Exotic trees.—A great many trees from other parts of the United
States and from Europe have been planted in Colorado for their fruit or
for shade and ornament. Apples and plums do well at the western edge
of the great plains next the foothills, while in the Grand Valley, on the
western slope, peaches are much grown. Most of the ordinary shade
trees of the eastern United States may be grown at Denver; such as
honey locust, black locust, elms, maples, ash, sycamore and catalpa.
Trees planted for forest purposes are chiefly black locust, honey locust,

t RooSEVELT, THEODORE, “‘ Message to the Congress of the United States,’” December 8, 1908,

FOREST FORMATIONS AND FOREST TREES si

black walnut and hardy catalpa. Rock pines are especially desirable
for hillsides and in poorsoil. The deciduous trees are more often
planted in the fine-grained soil of the plains region. Unless grown
on bottom lands all trees planted in Colorado must be irrigated or
else well cultivated and protected during the first few years after
being planted.

Scope of the present study.—The following pages are given up to
keys for the determination of the species of trees in the state, together
with a somewhat full account of each of the trees of the pine family.
It was thought best to describe these trees in some detail on account of
their economic value and the general interest which attaches to them.
It is impossible at the present time to state fully the distribution of most
of the species within the state. Only a small part of the area has been
examined by botanists so that the limits of distribution are imperfectly
known.

How to use the keys.—It is necessary to look at Key I for the “ever-
greens”’ (trees of the pine family) and at Key II for any other trees. In
each of the keys two choices are open to the student at first, named
respectively 1a and 1b. These two are to be read carefully and which-
ever describes the tree under. consideration will be used as the beginning
of the classification. At the right of line. is a figure in parenthesis
which refers the user of the key to the next line which is to be
consulted. This may give at once the desired name or it may
refer to a still lower line. At any rate the process is to be continued
until the name of the genus is found. Noting the number of the
genus, as well as the name, the student should now turn to the proper
place in the following pages and, with the aid of the special key, deter-
mine the exact species. Both the scientific and English names are
given since both are likely to be useful to one interested in botany or
forestry.

KEY I. FOR IDENTIFICATION OF COLORADO EVERGREENS
ta. Trees with needle-like foliage leaves; fruit a cone. (2)

tb. Trees with scale-like, overlapping leaves, fruit a small berry (cedars).
Genus 5. Sabina

52

_ 2a.

2b.

3a.

WILD FLOWERS AND TREES OF COLORADO

Foliage leaves (needles) in bundles of two or more surrounded at base by a short
sheath. Leaves mostly more than 25 mm. (1 in.) long. Cones hard and woody
when mature. Genus 1. Pinus

Foliage leaves (needles) solitary, not in bundles; mostly less than 25 mm. (1 in.)
in length. Mature cones leathery or papery; not hard and woody. (3)

Leaves jointed near the base, the lower part of the leaf brown and woody and remain-
ing on the branchlet after the rest of the leaf has fallen. Leaves in our species stiff
and four-angled, not flat. Cones pendulous. Genus 2. Picea

Fic. 45.—LEAVES OF CONIFEROUS TREES. 1. Pine (Pinus); 2. Douglas Spruce

(Pseudotsuga); 3. Spruce (Picea); 4. Fir (Abies).

}

3b.

4a.

4b.

Ia.
Ib.

Leaves not brown nor woody at base, flat. When they fall off they leave a scar but
no part of the leaf remains. (4)

Leaves rather soft; narrowed toward the base into a short stalk which broadens
slightly at the point of attachment. Leaf-scars transversely elliptical. Cones
pendulous, the projecting bracts three-pointed. Genus 3. Pseudotsuga

Leaves somewhat stiff, very slightly narrowed at base; leaf scars rather large, cir-
cular in outline. Cones erect, dark purple or blackish or sometimes yellow.
Genus 4. Abies

KEY II. FOR IDENTIFICATION OF DECIDUOUS TREES

Leaves simple; not composed of leaflets. (2)
Leaves compound; of three or more leaflets, (11)

FOREST FORMATIONS AND FOREST TREES 53

2a. Trees without thorns or spines. (3)
2b. Trees with thorns or spines. (10)
3a. Trees with rough bark of bitter taste; leaves much longer than broad; flowers and
fruits in erect catkins; seeds cottony (willows). Genus 7. Salix
3b. Trees with white or light gray branches; flowers and fruits in drooping catkins;
seeds cottony (cottonwoods, poplars and aspen). Genus 6. Populus
3c. Trees with conspicuous flowers and fleshy fruits (cherry, plum and June berry).
(4)
3d. Trees not falling under 3a, 3b or 3c. (5)
4a. Leaves with margin finely toothed all around (plum and cherry). S
Genus 15. Prunus
4b. Leaves with margin toothed only in the upper half (June berry).
Genus 13. Amelanchier
5a. Leaves with veining pinnate; a distinct mid-rib with lateral veins extending from
it, (6)
5b. Leaves with palmate veining; the main veins extending from the base of the leaf-
blade like fingers from the palm of the hand (maples). Genus 17. Acer
6a. Leaves elm-like; not symmetrical at base (hackberry). Genus 11. Celtis
6b. Leaves not elm-like; usually symmetrical at base. (7)
7a. Leaves very small; only 15 to 25 mm. (3 to 1 in.) long (mountain mahogany).
Genus 12. Cercocarpus
7b. Leaves mostly 35 mm. (1% in.) long, or longer. (8)
8a. Leaves pinnately lobed or cleft; the lobes and sinuses rounded; fruit an acorn
(oaks). Genus 10. Quercus
8b. Leaves merely toothed or slightly sharp-lobed; flowers and fruits in catkins (alders
and birches). ‘ (g)
8c. Leaves finely toothed or nearly entire; fruit berry-like, in small clusters (cascara
sagrada). Genus 19. Rhamnus
8d. Leaves finely toothed or wavy margined; fruit a winged samara (ash).

Genus 20. Fraxinus
ga. Leaves rough and coarse; with both fine and coarse teeth (alder). Genus 9. Alnus
gb. Leaves rather smooth; bright green. Genus 8. Betula

roa. Spines numerous, sharp pointed (thornapple). Genus 14. Crataegus
rob. Spines few, scattered (plum). Genus 15 Prunus
11a. Trees with short thorns in pairs (locust). Genus 16. Robinia
rb. Trees without thorns; leaflets more than four pairs (sumac). Genus 18. Rhus
11c. Trees without thorns; leaflets 3, 5 or 7 (box-elder). Genus 17. Acer

DESCRIPTIONS AND KEYS TO SPECIES
Genus 1. PINUS, PINE

Evergreen trees and shrubs growing often in dry and rocky situations.
Foliage leaves needle-shaped growing usually in bundles of 2 to 5

54 WILD FLOWERS AND TREES OF COLORADO

leaves. The foliage leaves are borne on very short twigs (dwarf shoots),
which arise in the axils of appressed scale leaves. Staminate cones
small, yellow or reddish, growing in clusters and shedding their pollen
in late spring or early summer. Carpellate cones either solitary or
clustered. Cone scales thick, becoming woody. The cones ripen the
second year or later.

ra. Leaves in bundles of 4 to 6; medium-sized or small trees, chiefly in high altitudes.

(2)

rb. Leaves in bundles of 2 or 3. (3)

2a. Leaves 25 to 4o mm. (1 to rf in.) long. Cones 7 to g cm. (23 to 3} in.) long, the
scales with curved, needle-pointed spines. Pinus aristata

2b

Leaves 3.5 to 7.5 cm. (1# to 3 in.) long. Tree of wind-swept mountain sides or
exposed points. Cones large, 7 to 25 cm. (2% to g# in.) long, the scales smooth,
without spines Pinus flexilis

3a. Leaves short, 2 to 4 cm. ($ to 1} in.) long, generally in pairs; cones small, about the
same length as the leaves, seeds large (about the size of a common white bean),
edible. A tree or shrub found in the foothills south and west. Pinus edulis

3b. Leaves longer, 4 to 12 cm. (13 to 4$ in.) long; in bundles of 2 or 3. (4)

4a. Leaves usually about ro cm. (3% in.) long, but shorter in exposed situations; some-
times longer. Cones 6 to 9 cm. (23 to 34 in.). A tree of foothills and river bluffs
and extending occasionally to an altitude of 10,000 ft. Pinus scopulorum

4b. Leaves 3 to 6 cm. (1} to 2§ in.) long; cones about same length as leaves. A tree of
foothills and mountains, often forming pure forests at altitudes of 8,000 to 10,000 ft.

Pinus murrayana

Pinus aristata Engelm. BRisTLE-cONE PINE. Leaves in bundles of 4 or 5,
dark green, 2.5 to 4.cm. long. Cone 7 tog cm. long. Cone scales somewhat thin, each
with a slender curved bristle about 6 mm. long. Seeds winged.

A bushy tree of small or medium size with the main trunk short, numerous strong
branches starting rather low down. Bark thin, pale or milky white on small branchlets,
dark gray or brown on the main trunk. Wood soft and not durable; specific gravity
0.5572.

Rocky and gravelly slopes at high altitudes in the mountains from central and
southern Colorado to Utah, Nevada, southern California and Arizona.

Pinus flexilis James. Limper PINE, WHITE PINE. Leaves in bundles of 5;
stout, rigid, dark green, 3.5 to 7.5 cm. long. Cone very large, 7 to 25 cm. long. Cone
scales smooth, without bristle points. Seeds large, with a narrow wing which usually
adheres to the cone scale when the seeds drop.

A medium-sized tree with a short main trunk and abundant lateral branches, growing
in wind-swept situations and hence often much distorted. Bark of twigs and branches
pale gray or whitish, becoming dark brown on older trunks. Wood light; specific gravity
0.4358; sometimes used for lumber which is, however, full of knots.

FOREST FORMATIONS AND FOREST TREES 55

Eastern slope of Rocky Mountains from Alberta to western Texas, westward through
Montana to Nevada and California. It is the principal tree of the upper foothills of the
eastern slope in Montana. In Nevada it forms extensive forests. In Colorado and Wyom-
ing it is usually scattered in exposed situations at rather high altitudes but a few trees are
found on the bluffs west of Pawnee Buttes, Colo., at an altitude of 5,00c feet.

Pinus edulis Engelm. Prnyon, Nut Pine. Leaves in bundles of z, rarely 3;
dark green, curved, stiff, 2 to 4.cm. long. Cone when mature about the same length as the
leaves and nearly spherical; cone scales few, thick, spiny tipped. Seeds large, about the
size of a small white bean, the narrow wing of the seed remaining adherent to the cone
scale when the seed falls. | :

A small or medium-sized tree, much branched and shrublike. Bark rather thin; that
of young branchlets orange colored, becoming at length gray or brown. Wood rather
durable; specific gravity 0.6388; brittle, close grained. Used for fuel and fencing and
sometimes for preparation of charcoal. In western Texas it has been sawed for lumber.
The large, edible seeds, known as “‘pinyon nuts,” collected by Indians, are on sale by fruit
dealers in the towns and cities of Colorado.

Eastern foothills of the outer range of the Rocky Mountains from near the Palmer
Lake divide south to western Texas and west to Arizona and southwestern Wyoming.
In places it forms open forests with the rock pine; mixed with cedars it is common on the
hills and table lands of western Colorado. It does not extend to very high altitudes.

Pinus scopulorum (Engelm.) Lemmon. Rock Pine. Leaves in bundles of
two or three, variable as to number even on the same tree; stout, dark yellowish-green,
often in bottle-brush arrangement at the ends of naked branches; 8 to15 cm. long. Cone
6 to g cm. long, the cone scales each with a stout sharp prickle. The young cones are erect
the first summer; when fully grown they are horizontal or slightly declining.

A handsome spreading tree, the largest of our pines, with thick, deeply-furrowed, red-
dish bark becoming very thick on old trees. Wood hard and strong but differing greatly
in quality; where abundant it is sawed into lumber or used for railway ties and mine tim-
bers. The specific gravity is 0.4619.

Hills and ridges of western Nebraska to Rocky Mountain region and from Montana to
Arizona and New Mexico.

On account of its resistance to drought this tree should be a valuable one for planting
in semi-arid districts. The large seeds germinate freely and the trees are easily grown
when given reasonable care. Sometimes called ‘yellow pine” or “blackjack.”

Pinus murrayana “‘Oreg. Com.’’ LopGEPOLE PINE. Leaves in bundles of 2,
yellow-green, 3 to 6 cm. long. Cone about the same length as the leaves, very persistent,
often remaining attached three or four years after ripening; cone scales with short, sharp
prickles. ;

A tall, straight tree, generally growing in dense groves on north slopes in the higher
foothills. The trees have been considered of little value for lumber but they are certainly
most useful in holding the soil and in protecting snow from too rapid melting. Seeds of
this pine, unlike those of most species, retain their vitality for a number of years. Burned
districts become reseeded by the opening of the cones which takes place on account of the
heat produced by the fire. Wood rather light and soft, not durable; specific gravity 0.4096.
Used to some extent for ties, mine timber and fuel when better wood is not available.

56 WILD FLOWERS AND TREES OF COLORADO

Recently developed methods of seasoning and preservative treatment promise to make the
lodgepole pine valuable for railway ties and mine timbers.

Montana to southern Colorado, west to California and Alaska. In the higher foot-
hills of Colorado.

Genus 2. PICEA, THE TRUE SPRUCES

Tall, conical, evergreen trees with tapering trunk and thin, scaly
bark. Leaves needle-shaped, four-angled or flattened (ours four-
angled) with sharp points. The leaves extend out from all sides of the
twig in bottle-brush fashion; they are not in bundles as in pine but occur
singly. Leaves jointed near the base, the lower part (sterigma) becom-
ing woody and persistent after the fall of the leaf. Bare twigs thus
appear roughened with short, truncate elevations. Cones pendant,
chiefly on the upper branches.

ta. Leaves rigid, needle pointed, blue-green or silvery, branchlets smooth or at least not
hairy. Cones about 7 cm. (2? in.) long. Frequent in cultivation. Picea parryana
Ib. Leaves less rigid, abruptly pointed, having a somewhat skunk-like odor when bruised.
The branchlets are generally described as pubescent but are smooth in specimens
grown at high altitudes. Cones about 4 cm. (1$ in.) long. Picea engelmanni

Picea parryana (Andree) Sarg. CoLorapo BLUE Spruce. Leaves stout,
rigid, four-angled, mostly 25 to 30 mm. long but on cone-bearing branches shorter and
curved. Generally the leaves stand out from all sides of the branchlets but sometimes
the under surface of horizontal branches has few leaves. Color of leaves generally silvery
or bluish-green when young, becoming duller with age. Individual specimens differ
greatly in this regard. Cones about 7 cm. long.

A tree of medium size. Bark broken into small oblong, platelike scales; on old
trunks thick and deeply grooved. Wood light, soft, weak; specific gravity 0.3740.

Along the mountain streams of eastern Colorado, west to Utah and north to the Wind
River Mountains of Wyoming, occurring singly or in small groves.

Much cultivated for ornament in this country and in Europe. There are numerous
horticultural varieties propagated by grafting.

Picea engelmanni (Parry) Engelm. ENGELMANN SPRUCE. Leaves ridged above
and below so that they are rather four-sided; awl pointed; not so stiff as those of the blue
spruce. Leaves at first covered with a bluish or silvery bloom which disappears later;
slender, 25 to 30 mm. long on the ordinary branches but shorter on cone-bearing twigs.
Cones 3 to 5 cm. long.

A large conical tree of the higher foothills and mountains; near timber limit a strag-
gling, prostrate shrub. Bark thin, broken into large, thin, loose scales. Wood light, soft,
close grained, not strong; specific gravity 0.3449. Frequently used for lumber and for
making charcoal. The bark has been employed for tanning leather. In some localities
the Englemann spruce has been largely cut for railway ties and to some extent for telegraph
and telephone poles. It should be valuable for wood pulp.

FOREST FORMATIONS AND FOREST TREES 57

In the Cascade, Selkirk and Rocky Mountain ranges of British Columbia and Alberta,
south through the mountain states to New Mexico and Arizona, west to Oregon. It is
by far the more abundant of our two species of Picea and is the common tree near timber-
line where it forms scrubby mats. In such situations it seldom bears cones. At 10,000
to 11,000 feet altitude it reaches its largest size. :

The Engelmann spruce has been planted for ornament in the eastern United States
and in Europe. Sometimes it is mistaken for the blue spruce. These two species of
Picea are not easily distinguished; however, the size of the cones is a marked feature.

Genus 3. PSEUDOTSUGA, Dovuctas SpRUCcE

Tall conical trees with thick, furrowed bark and strong wood resem-
bling in quality the best hard pine. Branches generally ascending, the
branchlets spreading; general appearance more feathery than true
spruce. Leaves linear, flat, narrowed at base to a short. leaf-stalk.
Cones pendant; usually scattered over the tree; not confined to the
upper branches; cone scales persistent; bracts with prominent teeth
giving the cone a fringed appearance. ‘Three species of this genus are
known; one in Japan, two in western North America.

Pseudotsuga mucronata (Raf.) Sudw. Dovctas Spruce. Leaves rather soft,
not rigid, flat, channeled above and ridged below, 20 to 35 mm. long, dark yellow-green in
color, narrowed to a short stalk; leaf scars not prominent. Cones pendulous, 5 to ro cm.
long, the bracts projecting beyond the scales. Each bract with two lateral teeth and the
midrib projected as a rigid awn.

A tree of handsome conical form, especially when young; reaching the greatest size
in the moist forests of Oregon and Washington. Bark on young trees smooth and thin;
on older trees very thick and deeply furrowed. Wood hard; light red or yellow; specific
gravity 0.5157; largely manufactured into lumber in the Pacific Northwest where it is
generally known as “Oregon pine,” ‘Douglas fir’ and ‘red fir.” Employed for fuel,
railway ties and piles; in Colorado used as Christmas trees.

British Columbia and Alberta southward through hills and mountains to northern
Mexico and western Texas. .

Frequently planted as an ornamental and shade tree in Europe and the eastern United
States. Numerous varieties are distinguished in cultivation.

Genus 4. ABIES, THE Firs, BALSAMS

Tall conical trees of colder regions and mountain districts. Leaves
linear, flat, sessile; grooved above and having a notched apex. On the
upper cone-bearing branches the leaves are often curved and thick, with
the upper surface convex instead of grooved. Cones erect; purplish-
black or yellow, formed of closely overlapping scales; exuding a bal-

58 WILD FLOWERS AND TREES OF COLORADO

samicresin. The cone-scales and bracts separate from the axis while this
is still on the tree; hence complete cones are never found under the
trees.

ta. Leaves of vigorous lower branches 2.5 to 4.5 cm. (1 to 1? in.) long; resin ducts of the
leaves deeply imbedded, not close to the epidermis. Cones purple or nearly black.
Abies lasiocarpa

Ib. Leaves of vigorous lower branches 4.5 to 7.5 cm. (13 to 3 in.) long; resin ducts of the
leaves close to the epidermis of the under surface; cones yellow, green or purple.
Not found in northern Colorado.’ Abies concolor

Abies lasiocarpa (Hook.) Nutt. SuB-aLPIne Fir. Leaves flat, with prominent
mid-vein, bluish-green; on vigorous lower branches 2.5 to 4.5 cm. long; on old parts and
on cone-bearing twigs much shorter. Cone oblong-cylindrical, rounded, erect, purple or
nearly black, 6 to 10 cm. long.

A medium-sized tree with branches extending nearly to the base of the trunk; bark
of young trees pale gray and smooth; on old trees broken with shallow fissures and rough-
ened with thin orange-colored scales. Wood light, not strong, nor durable; of little value
but sometimes used as firewood; specific gravity 0.3476.

High altitudes in the mountains throughout western North America.

Abies concolor Lindl. Wate Fir. Leaves mostly in two rows on the branch-
lets, more or less erect; on lower branches flat, straight, with rounded or pointed apex;
length 4.5 to 7.5 cm.; on cone-bearing twigs shorter and generally curved. Cone ellipsoid-
cylindrical, 7 to 13 cm. long, grayish-green, purple or yellow, with broad, closely imbri-
cated scales. A large tree with narrow spire-like crown; the short, main branches bearing
long, lateral branchlets; the whole forming frond-like masses of foliage. Bark of old
trunks becoming very thick, deeply divided into broad, rounded ridges. Wood light,
close grained, not strong nor durable; specific gravity 0.3638.

From the Pike’s Peak region of the Rocky Mountains of Colorado west to Oregon
and south to northern Mexico and Arizona, reaching its greatest development in the Sierras
of California. It is the only true fir in the arid regions of the Great Basin.

Genus 5. SABINA, CEDAR

The trees and shrubs of this genus are often classified with the
junipers and placed in the genus Juniperus. It seems best to separate
them because the cedars have such a very different general appearance.
Leaves of true junipers are sharp-pointed and awl-shaped; instead of
being scale-like and rather soft to the touch, as are the leaves of cedars.
It is to be noted, however, that the leaves of young cedars are sharp-
pointed and look like the leaves of junipers.

ta. Fruit when ripe blue, juicy, resinous. (2)

1b. Fruit when ripe reddish-brown, dry, fibrous. Small tree of western Colorado and
westward. Sabina utahensis (Engelm.) Rydb.

2a.

2b.

FOREST FORMATIONS AND FOREST TREES 59

Leaves with minute teeth near the apex; fruit generally one-seeded.

Sabina monosperma (Engelm.) Rydb.
Leaves entire at apex; fruit generally several-seeded. The common cedar of the
eastern slope. Sabina scopulorum (Sarg.) Rydb.

Fic. 46.—Rocky Mountain Rep CEpar (Sabina scopulorum). X}

Genus 6. POPULUS, Poplars, CoTroNwoops, ASPEN

These are the most important trees of the river-bottom and canyon

forests. The broadleaf cottonwoods seldom extend far up the canyons
and the narrowleaf trees seldom get down to the lower altitudes of the
plains region.

Ta.

Ib.

2a.

2b

2¢.

Leaf-stalk much flattened laterally where attached to blade of leaf. Leaves easily

rustled by the wind. (2)
Leaf-stalk nearly cylindrical where attached to blade. (3)
Leaf-blade somewhat circular in outline with short-pointed apex. Bark very white.

: Populus tremuloides Michx.

“Quaking Aspen”
Leaf-blade broadly triangular or heart-shaped; marginal teeth less than ten on each
side of blade (tree of southern Colorado). Populus wislizeni (Wats.) Sarg.
“Broadleaf Cottonwood”

Leaf-blade broadly triangular or heart-shaped; marginal teeth more than ten on

each side of blade. (This is the common broadleaf cottonwood at Denver and in
northern Colorado.) Populus sargentii Dode.
“Broadleaf Cottonwood”

60 WILD FLOWERS AND TREES OF COLORADO

Fic. a OF DIFFERENT SPECIES OF PoPULUS ee

1. Populus angustifolia 2. Populus acuminata
3. Populus tremuloides 4. Populus halsamifera

61

FOREST FORMATIONS AND FOREST TREES

rgentit). X4

Fic. 48.—BROADLEAF CoTTonwoop (Populus sa.

62 WILD FLOWERS AND TREES OF COLORADO

3a. Leaf-stalk stout; one-third the length of blade or less; blades narrow.
Populus angustifolia James.

“Narrowleaf Cottonwood”
3b. Leaf-stalk slender, one-half the length of blade or longer. (4)

Fic. 49.—NARROWLEAF Cottonwoop (Populus angustifolia). X4

4a. Leaf-blades ovate; rounded at base, under surface whitish; veins prominent. Trees
of mountain districts. Populus balsamifera Linn.
“Balsam Poplar”

4b. Leaf-blades lance-ovate, generally narrowed at base. Tree of canyons and the
plains region. Populus acuminata Rydb,
“Lanceleaf Cottonwood”

FOREST FORMATIONS AND FOREST TREES 63

Genus 7. SALIX, WitLtow

In addition to the trees here listed there are about twenty species of
shrubs in Colorado belonging to the genus Salix. Some of these extend
above timberline, forming, in places, dense thickets three or four feet

high.
ta. Leaves-lanceolate, finely serrate, pointed. (2)
1b. Leaves ovate, finely toothed or nearly entire, sometimes lance-elliptic or ob-ovate.
(3)
1c. Leaves linear or narrowly lanceolate, silvery, at least when young. (4)
»
Fic. 50.—NARROWLEAF WILLOW (Salix exigua). X}
2a. Young twigs usually hairy; leaves firm. Salix lasiandra Benth.
“Western Black Willow”
2b. Young twigs smooth; leaves thin. Salix amygdaloides Anders.
“Peach Willow”
3a. Upper surface of leaves dark green; lower surface pale. Salix nuttallii Sarg.
“Nuttall’s Willow”
3b. Upper surface of leaves pale; lower surface dull. Salix bebbiana Sarg.
: “Bebb’s Willow”
4a. Capsule glabrous when mature. Salix exigua Nutt.
: “Narrowleaf Willow”’
4b. Capsule densely white-silky, even when mature. Salix sessilifolia Nutt.

“Narrowleaf Willow”

Genus 8. BETULA, BircH

In addition to the two trees of this genus there is a dwarf shrub
(Betula glandulosa Michx.) along streams at high altitudes.

64 WILD FLOWERS AND TREES OF COLORADO

ta. Bark of trunk brownish-gray; fertile catkins about 15 mm. ({ in.) long.
Betula fontinalis Sarg.
“Canyon Birch”

tb. Bark of trunk pale gray or light brownish; fertile catkins about 30 mm. (1} in.) long
Betula andrewsii A. Nels.
“ Andrews’ Birch”

(Wf
\ are RES

T:

fe

ESI
SHAR ERY

etter
d
Ay
e

Fic. 51.—Canyon Birca (Betula jontinalis). X}

Genus 9. ALNUS, ALDER

This genus is represented by a single species, a tree or shrub growing
Leaves broadly ovate, doubly toothed.

in clumps along streams.
Alnus tenuifolia Nutt.
“ Alder”

FOREST FORMATIONS AND FOREST TREES 65

Fic. 52.—ALDER (Alnus tenuifolia). X}

Genus 10. QUERCUS, Oak

Eleven species of oak are recorded by Rydberg as occurring in Colo-
rado. They are found in the foothill districts at moderate altitudes,
chiefly in the southern and western parts of the state. The following
are the only trees.

1a. Leaves at maturity velvety beneath. Quercus utahensis (DC.) Rydb.
“Utah Oak”

Ib. Leaves at maturity smooth or downy but never velvety beneath. (2)

2a. Mature ‘eaves very thin. Quercus leptophylla Rydb.

“Colorado Oak”
2b. Mature leaves firm. (3)

66 WILD FLOWERS AND TREES OF COLORADO

3a. Leaves ob-ovate in outline; cleft half-way to the mid-rib or less; acorns acute,
Quercus gambellii!Nutt.
“Gambell’s Oak”

3b. Leaves ob-ovate in outline; cleft deeper than half-way to the mid-rib; acorns obtuse,
Quercus nitescens Rydb.
“Shining Oak”

FIG. 53.—SHINING OAK (Quercus nitescens). X}

Genus 11. CELTIS, HackBErry

These trees have much the appearance of elms. The leaves are
oblique at base and the trunk is rough and deeply furrowed. -

1a. Leaves broadly ovate; acute or short pointed at apex; ripe fruit red.
Celtis reticulata Torr.
“Thick-leaved Hackberry”
1b. Leaves ovate, often long pointed at apex; ripe fruit black. Celtis douglasii Planch.
; “Douglas Hackberry”

FOREST FORMATIONS AND FOREST TREES 67

Fic. 54.—THICK-LEAVED HACKBERRY (Celtis recticulata). X4

Genus 12. CERCOCARPUS, Mountain MaHocGANny

In addition to the species named below there is a shrubby Cerco-
carpus which has dentate leaves; very abundant on the rock ridges and
lower foothills east of the divide.

ta. Tree or shrub with very small entire leaves; fruit seed-like with long plumose tail.
.<, Found on the western slope of the Rocky Mountains. Cercocarpus ledifolius Nutt.

Fic. 55.—Mountain Manocany Fic. 56.—J UNE BERRY (Amelanchier
(Cercocar pus ledifolius). X. alnijolia). X}.

68 WILD FLOWERS AND TREES OF COLORADO

Genus 13. AMELANCHIER, JuNE Berry, SERVICE BERRY

Seven species of this genus are recorded from the state, all but the
following being shrubs.

Ia. Small tree or shrub on hillsides or in canyons; the fruit a pome; leaves toothed only
near the apex. Amelanchier alnifolia Nutt.

Genus 14. CRATAEGUS, THORNAPPLE

Trees or shrubs with stout spines and handsome white flowers; grow-
ing along streams in the foothill region. Fruit, red, black, brown or
orange.

i

LoXy)

Fic. 57.—Colorapo THORNAPPLE (Crataegus Fic. 58.—ST. LAWRENCE THORNAPPLE
colcradensis). X}. (Crataegus laurentiana). X}.
‘Ia. Spines long, 3 to 8 cm. (1} to 3 in.). (2)
tb. Spines short, about 2 cm. (2 in.). (7)
2a. Anthers pink or crimson. (3)

2b. Anthers white or cream. (4)

FOREST FORMATIONS AND (FOREST TREES 69

Fic. 61.—SMALL-LEAVED THORNAPPLE Fic. 62.—SHINY-LEAVED THORNAPPLE (Crataegus

70 WILD FLOWERS AND TREES OF COLORADO

3a. Pedicels glabrous. Crataegus cerronis A. Nels.
“‘Shiny-leaved Thornapple”

3b. Pedicels somewhat villous; leaves broadly ovate, Crataegus coloradensis A. Nels.
“Colorado Thornapple”

3c. Pedicels densely villous at flowering time; becoming nearly glabrous; leaves ob-
ovate, wedge-shaped at base. Crataegus laurentiana Sarg. :
“St. Lawrence Thornapple”

4a. Shoots becoming glabrous or nearly so at close of first year; leaf serrations glandular.
(s)

4b. Shoots villous or pubescent throughout the first year; leaf serrations not glandular.

5a. Leaves at maturity with scattered villous pubescence below, especially on the veins;
fruit dark red. Crataegus doddsii Ramaley.
“Thick-leaved Thornapple”

6a. Petiole about 4 the length of the blade; leaf-apex often obtuse.
Crataegus occidentalis Britt.
“Western Thornapple”

6b. Petiole about 4 to $ the length of the blade; leaf-apex often somewhat truncate. 5
: Crataegus coloradoides Ramaley.
“Canyon Thornapple”

va. Leaves ovate, simply serrate or crenate, 2 to 4cm. broad. Crataegus rivularis Nutt.
“River-bank Thornapple”

7b. Leaves lanceolate, serrate, sometimes obscurely lobed; only 1 to 2 cm. broad (generally
about 1.5 cm.). Crataegus saligna Greene.
“Small-leaved Thornapple”

Genus 15. PRUNUS, Plum AND CHERRY

Four species of Prunus are recognized as occurring in Colorado.
One is the common wild plum so abundant at canyon mouths in the
foothills; the others are cherries. Of the latter, Prunus besseyi is a
dwarf species, often a mere trailing or prostrate shrub.

ta. Flowers and fruits in long racemes; fruit black when ripe.
Prunus melanocarpa (A. Nels.) Rydb.
“Choke Cherry”’

1b. Flowers and fruits in short umbels or corymbs. (2)

2a. Leaves bright green and shining above; fruit red, 5 to 7 mm. (about } in.). in diameter.
Prunus pennsylvanica Linn. f.
“Wild Red Cherry”

2b. Leaves dull green above; fruit 20 to 25 mm. (} to 1 in.) in diameter.
Prunus americana Marsh.
“Wild Plum”

FOREST FORMATIONS AND FOREST TREES 71

72 WILD FLOWERS AND TREES OF COLORADO

Ta

Ib
2a

2b

SUNS

Fic. 64.—CHoxke CHERRY (Prunus melanocarpa). x4

Genus 16. ROBINIA, Locust

The native Colorado locust is closely related to the common black
locust or yellow locust now so often planted for posts and railway ties.

1a. Small tree or shrub with pinnately compound leaves and pink, pea-like flowers, pro-
ducing many-seeded pods. Along streams in southern part of state.
Robinia neo-mexicana A. Gray.

“Pink Locust”
Genus 17. ACER, Maries AnD Box-ELDER
. Leaves compound, of 3, 5 or 7 leaflets. Acer interior Britt.
2 “Box-Elder”
. Leaves simple; palmately veined. (2)

. Leaves longer than broad; generally three-lobed, margins distinctly serrate.
: Acer glabrum Torr.
“Rocky Mountain Maple”
. Leaves broader than long; three to five-lobed; margins not serrate.
Acer grandidentatum Nutt.
“Mountain Sugar Maple”

FOREST FORMATIONS AND FOREST TREES 73

Fic. 66.—Rocky Mountain Maple (Acer
glabrum). X4.

Fic. 67.—Box ELDER (Acer interior). X¥. Fic. 68.—Sumac (Rhus glabra). X34.

74 WILD FLOWERS AND TREES OF COLORADO

Genus 18. RHUS, Sumac

This genus is represented in Colorado by Rhus rydbergii, the western
poison ivy and Rhus trilobata, the common “skunk bush,” in addition to
the following species.

1a. Usually a shrub but often tree-like at canyon mouths in rich, well-watered soil. Leaves
compound, of numerous pointed leaflets; turning to red or crimson in autumn.
Rhus glabra Linn.
“Sumac”

Genus 19. RHAMNUS, BuckTHoRN

ta. Tree of western Colorado and westward; elliptical leaves; small greenish flowers;
black berry-like fruits. The bark has medicinal properties.
Rhamnous purshiana DC.
“Cascara sagrada”’

Fic. 69.—Cascara SAGRADA (Rham-
nus burshiana). X 4.

Fic. 70.—AsH (Fraxinus anomala), X}.

Genus 20. FRAXINUS, Asu

Related to the “white ash” and “green ash” so commonly planted
for shade. The Colorado species has the typical flower and fruit struc-
ture of the ash but the leaf is not usually compound.

ta. Leaf simple, or occasionally with two or three leaflets; fruita winged samara. Occur-
ring in canyons of the southwestern part of the state.
Fraxinus anomala Torr.

FOREST FORMATIONS AND FOREST TREES 75

PartTIAL List oF Books AND SPECIAL ARTICLES DEALING WITH COLORADO TREES

AsHE, W. W., “New North American Plants; Some New Species of Crataegus,” Ann.
Rep. No. 24, N.C. Coll. of Agric. and Mech. Arts, June 30, 1901.

BENNETT, Mrs. Cora, “List of Colorado Trees,” Plant World, Vol. XI, p. 66, 1908.

Britton, N. L., North American Trees, pp. 1-894, New York, 1908.

CLEMENTS, FREDERIC E., ‘Formation and Succession Herbaria,” University of Nebrasha
Studies, Vol. IV, pp. 329-355- .

CockErELL, T. D. A., “The Genus Crataegus in Colorado,” University of Colorado
Studies, Vol. V, pp. 41-45, 1907.

Cooper, W. S., “Alpine Vegetation in the Vicinity of Long’s Peak, Colo.,” Botanical
Gazette, Vol. XLV, pp. 319-333, 1908.

COULTER, JOHN M., Manual of Botany of the Rocky Mountain Region, New York (1882 ?),
PPp- 1-453-

Donpps, GipeEon S., “Studies of Mesa and Foothill Vegetation; Geology and Physiography
of the Mesas,”” University of Colorado Studies, Vol. VI, pp. 11-19, 1908.

Dopps, GIDEON S., AND Rosgins, W. W., “Studies of Mesa and Foothill Vegetation;
Distribution of Conifers on the Mesas,” University of Colorado Siudies, Vol. VI,
PP. 31-36, 1908.

ENSIGN, Epcar T., “ Report of Forest Conditions in the Rocky Mountains,” Bull. No. 2,
Forestry Division, Department of Agriculture (2d ed.), pp. 141-153, 1889.

GaNNETT, HENRY, ‘The Forests of the United States,” rgih Annual Report U. S. Geol.
Survey, Part V, pp. 1-26, 1897-98; 20th Annual Report, pp. 1-38, 1898-99; 2rst
Annual Report, pp. 13-15, 1899-1900.

Jack, Joun G., ‘‘List of Trees and Shrubs Observed in the Pike’s Peak, Plum Creek
and South Platte Reserves,” 20th Annual Report, U. S. Geol. Survey, Part V, pp.
Iog-115, 1898-99; ‘‘Pike’s Peak, Plum Creek and South Platte Reserves,” pp.
39-108, same publication.

Mitts, Enos A., AND STONE, W. G. M., Forest and Exotic Trees of Colorado (Pamphlet),
Denver, 1905. ; :

-NEtson, AVEN, Analytical Key to Some of the Common Flowering Plants of the Rocky
Mountain Region, pp. 1-94, New York, 19go2.

—, ‘Plantae Andrewsii,” Proc. Biol. Society Wash., Vol. XVII, pp. 173-180, 1904.

RAMALEY, FRANcIS, ‘Remarks on the Distribution of Plants in Colorado East of the
Divide,” Postelsia; Yearbook of the Minn. Seaside Station, pp. 21-53, 1901.

, ‘The Silva of Colorado; Trees of the Pine Family,” University of Colorado Studies,

Vol. IV, pp. 109-122, 1907; “The Silva of Colorado; Poplars, Aspens and Cotton-

woods,” Vol. IV, pp. 187-197, 1907; ‘‘The Silva of Colorado; Woody Plants of

Boulder County,” Vol. V, pp. 47-63, 1907.

, ‘Plant Zones in the Rocky Mountains of Colorado,” Science (New Series), Vol.

XXVI, pp. 642, 643, 1907.

, “Botany of Northeastern Larimer Qounty, Colorado,” University of Colorado

Studies, Vol. V, pp. 119-131, 1908.

, “Studies of Mesa and Foothill Vegetation, Climatology of Mesas,” University

of Colorado Studies, Vol. V1, pp. 19-31, 1908.

-, “New Colorado Species of Crataegus,”’ Botanical Gazette, Vol. XLVI, pp. 381-384,

1908.

76 WILD FLOWERS AND TREES OF COLORADO

RAMALEY, FRANCIS, AND Dopps, G. S., “Two Imperfectly Known Species of Crataegus,”
Bull. Torrey Botanical Club, Vol. XXXV, pp. 581-583, 1908.

, AND Rossins, W. W., “Studies in Lake and Streamside Vegetation; Redrock
Lake near Ward, Colo.,” University of Colorado Studies, Vol. VI, pp. 133-168, 1909.

Rossins, W. W., “Studies of Mesa and Foothill Vegetation; Deciduous Trees and Shrubs
of the Mesas,”’ University of Colorado Studies, Vol. VI, pp. 36-47, 1908.

, AND Dopps, G. S., “Studies in Mesa and Foothill Vegetation; Distribution of Con-
ifers on the Mesas,” University of Colorado Studies, Vol. V1, pp. 31-36, 1908.

RorHrock, J. T., ‘Notes on Colorado,” U. S. Geog. Surv. West of the tooth Meridian
(Wheeler Report), Vol. VI, pp. 1-15.

RypBEre, P. A., “The Oaks of the Continental Divide North of Mexico,” Bull. N. Y.
Botanical Garden, 1got.

, Flora of Colorado, Bull. 100, Colo. Agric. Coll. Exper. Sta., pp. 1-447, Ft. Collins,
Colo.,' 1906.

SARGENT, CHARLES S., Report on the Forests of North America; 1oth Census of the United
States, Vol. IX, Washington, 1884.

a , Manual of the Trees of North America, pp. 1826, Boston, 1905.

ScHNEIDER, E. C., ‘‘The Distribution of Woody Plants in the Pikes’ Peak Region,”
Colorado College Publications (Science Series), Vol. XII, pp. 137-170, 1909.

Younc, Rosert T., “Forest Formations of Boulder County, Colorado,”
Gazette, Vol. XLVI, pp. 321-352, 1907. i

Botanical

ALPHABETICAL INDEX OF WILD FLOWERS

Abies concolor
lasiocarpa

Acer glabrum
grandidentatum
interior

Alder .

Alnus tenuifolia

Amelanchier alnifolia

Anemone

Aquilegia coerulea

Argemone intermedia

Ash

Aspen .

Beard tongue

Betula andrewsii .
fontinalis.

Big trees .

Birch .

Buckthorn ;

Campanula petiolata

Campion

Cascara sagrada .

Cercocarpus ledifolius

Cedar .

Celtis douglasii
reticulata.

Clementsia rhodantha

Colorado blue spruce

Crataegus cerronis
coloradensis .
coloradoides
doddsii
laurentiana
occidentalis
rivularis
saligna

Douglas spruce

Cottonwood

Elephantella groenlandica .

Erigeron macranthus .

AND TREES
PAGE
58 Eriogonum umbellatum
58 Eritrichium argentium
3 92 Evening primrose
i 2 Pir og es
72 Forget-me-not
64 Fraxinus anomala
64 Grasses
68 Hackberry
9 Harebell
22 Hawthorn
5 Juniper
74 Leucrocrinum montanum
59 Little red elephant
26 Locust
64. Maple .
64 Mountain campion
18 Mountain daisy .
64 Mountain mahogany
74 Oak . ffs
32 Pachylophus caespitosa .
35 Pasque flower
74 Pentstemon alpinus
. 67 Picea engelmanni
58, 59 parrayana
66 Pine
66, 67 Pinus aristata.
27 edulis.
45, 50 flexilis
70 murrayana
70 scopulorum
7o Pond lily
70° Poplar
70 Poppy, Prickly
70 Populus acuminata
7° angustifolia
70 balsamifera
57 sargentii
59, 61 tremuloides .
31 wislizeni .
2i Prickly poppy

77

sae 35

65, 66

53) 54, 55

25

59, 60, 61, 62
5

60, 62

60, 62

60, 62

59, 61

59, 60

59

5

78 WILD FLOWERS AND TREES OF COLORADO

PAGE PAGE
Primrose, Evening . . e Salix amygdaloides . . . . 63
Prunus americana. 70, 71 bebbiana «li. ‘ 63
melanocarpa. . 70, 72 exigua .. — - 63
pennsylvanica . 7° lasiandra sa 63
Pseudotsuga mucronata : we. oe nuttallii . ‘ 63
Pulsatilla hirsutissima 9 sessilifolia ty ke, a 63
Quaking aspen. 59, 60 Sandlily . . . ae 2,3
Quercus gambellii 66 Sedges ; . 25, 30
Quercus leptophylla oe « » 65 Silver spruce é a 45, 56
nitescens : : 66 Spruce... F 56
utahensis. . .. 65 Sulphur flower. . 15
Redorpine . . 27 Sumac : 73, 74
Rhamnus purshiana . ; 74 Thorn ae ite abe . 68, 69, 70
Rhus glabra . 27. . 73,74 Thornapple . . . 68, 69, 70
Robinia neo-mexicana .. 72, 73 Water lily . . . 25
Rydbergia grandiflora 34 Willow . . . . i 63
Sabina monosperma. . 59
scopulorum . . 59

utahensis. . A : 58