7^

r€

^^.^j-yy ^->

-E

^

The Vegetation of the

Yellowstone Hot

Springs.

By JOH: .( W. HARSHBERGER, Ph.D.

Reprint from

I

y

(

•^

THE VEGETATION OF THE YELLOWSTONE HOT

SPRINGS.
(V,

By John W. Harshberger, Ph.D.

The actual discovery of the Yellowstone Wonderland, by which
is meant its full and final disclosure to the world, was the work of
three parties, who visited and explored it in the years 1S69, 1870
and 1 87 1. Although, since the last date, much has been written
concerning the geological and physiographical features of the park
set aside by Act of Congress in the year 1872, little has been writ-
ten concerning the flora of the region, and what has been published
deals almost entirely with the plants from a systematic standpoint.

Situated in the northwestern corner of Wyoming, in the Rocky
Mountains, at an elevation ranging from 6,000 to 12,000 feet, the
region is one of high and lofty mountains, of deep caiions walled in
by precipitous sides, and of beautiful upland valleys, the natural
haunts of the timid herbivora that seek the mountain meadows for
the tender and nutritious grasses which grow there luxuriantly.
The pasturage in many of the meadows and valleys is excellent,
being formed by the growth of such grasses as alpine timothy,
Phleitvi alpinw>i,h\\iQ ]o\n\., Calaviagrostis Canadensis, sheep's fescue,
Festnca ovina, Kceleria, KceUria cristata. The herbaceous vegetation
is not so striking as in many other regions, but still the distribution
of such species as do occur is interesting. In the lakes and rivers
we find the aquatic vegetation to consist of Ranunculus aguatilis,
Nuphar advena, Nuphar polyceplialum, Utricularia vulgaris, Lenina
tnsulca, Typha latifolia, Sparganiiim simplex, etc. Near the head
of Yellowstone Lake is found Subiilaria aquatica, a plant of quite a
remarkable distribution, found nowhere else in America except in
Maine and New Hampshire. Gentiana deionsa, Spraguea unibellata
are striking plants. The meadows and hillsides are spangled with
bright-colored flowers, among which may be noted the bee larkspur,
Delphinium Mejiziesii, the columbine, Aquilegia flavescens, the hare-
bell. Campanula, \\i^ aconite, Aconifiim Columbiamnn, the lupine, Lu-
pinus, the evening primrose, CEnothera, the aster, the painted cup, Cas-
tilleia. It is a remarkable fact that scarcely a night passes through-
out the summer without frost, so that the herbaceous plants grow
and bloom under somewhat unusual conditions. The fringed gen-
tian, Gentiana dctonsa, closes its flowers as night approaches, to
open them again in the ni jrninj;, and many other plants provided

with a hairy or woolly covering are thus secure against frost action.
The plants of the Yellowstone region, as far as observed, are well
adapted to their surroundings.

The forests are formed by one tree predominating, P/«z/5 contorta,
var. Murrayana, which grows tall and straight, but never reaches
any considerable girth. Interspersed among the pines we find sev-
eral other arborescent species, namely, Douglass spruce, Pseiuiotsnga
Douglasti, the largest tree in the park; balsam, Abies subalpina, pine,
Pinus Engelniannii, red cedar, Juniperns Virginiana, poplar, Popii-
lus trenitdoides, and willow, Salix, of several species. These forests
are of great importance in conserving the rain which falls. Many
of the most important rivers of the western United States rise in
this region, the Missouri, the Yellowstone, the Wind, the Big Horn,
the Platte, the Green (afterward the Colorado), and the Snake,
which flows through Wyoming, Idaho and Washington, emptying
into the Columbia, and thus reaches the Pacific.

Yellowstone Park, notwithstanding its wild grandeur as a moun-
tain domain, is yet more interesting on account of the geological
wonders which are found within its boundaries, namely the geysers
and hot springs. The geysers are actively throwing up in jets at
periodic intervals, steam and boiling water ; the hot springs are
either quiescent, or are bubbling and boiling without explosive erup-
tion. They are found in four distinct areas in the Park; the geysers
and the hot springs in the Upper, Lower and Norris Geyser Basin,'
hot springs only in the Mammoth Hot Spring Region. This divis-
ion also accords with the predominating chemical content of the
waters. In the Upper, Lower and Norris Geyser Basins, we have
springs and geysers which are actively depositing silicious material
(sinter); in the Mammoth Hot Spring Basin, springs which are
forming calcareous deposits, called travertine.

Much inquiry hag been instituted concerning the therapeutic value
of the mineral springs of the Park. Many hot spring regions through-
out Europe and America are resorted to by thousands in search of
health. The hot springs of Virginia are visited by hundreds every
year. It is said of the Yellowstone region, that the first explorers
to ascend the Gardiner River, in 1871, found numbers ot mvaluls
encamped on the banks, where the hot waters from Manmioth Hwt
Springs enter the stream ; and it is recorded that they were most
emphatic in their favorable impressions in regard to their sanitary

effects. No one now goes to the Park on account of its mineral
waters. It would, therefore, be premature to assume that there is
no medicinal virtue in them. Two great drawbacks are to be
encountered, and these alone are sufficient to explain why the Yel-
lowstone will probably never become a resort for invalids. Inacces-
sibility, length and severity of the winters are sufficient obstacles
to the National Park ever becoming such a resort. The open
summer season lasts only about three months.

The hot springs and geysers, on the other hand, are interesting
to the geologist, because of the remarkable phenomena connected
with their origin and activity ; to the botanist they are fascinating,
because of the low forms of vegetal life found existing in them
even at high temperatures.

As before stated, the waters which run from the hot springs and
geysers of the Yellowstone m.ay be comprehended under two heads —
those which deposit silica, as sinter, and those which form calcium
carbonate, as travertine. The last-mentioned substance is only
found in the Mammoth Hot Spring Basin ; the latter makes up the
characteristic formations of the Norris, Lower and Upper Geyser
Basins. The question naturally arises, how are the beautiful terraces
which surround many of the hot spring centres formed ? Are they
not simply built up by the deposition of new material from the over-
flow water, as it evaporates and cools at the surface ? At first sight,
it would seem that the craters and bowls of the geysers and hot
springs were foimed in this way, because we know that boiling
water, under pressure, will dissolve and hold in solution much more
inorganic material than ordinary river or spring water at the normal
temperature, and that in many instances, when the pressure is
relieved and the temperature lowered, the water will precipitate its
mineral contents.

In the case of the richly carbonated waters of the Mammoth Hot
Springs, calcium carbonate is deposited by the relief of pressure, by
the escape of the carbon dioxide and by the evaporation of the
water ; but this physical process is not the sole cause of the varied
and beautiful terraces, which will presently be described. At the
Norris Geyser Basin, relief of pressure and cooling will cause a
separation of silica from the hot waters, but the waters of the other
geyser basins contain very much less silica, and, as far as has been
observed by geologists, neither relief of pressure nor cooling will

4

produce a separation of the silica. Water collected from the springs
and geysers of the Upper and Lower Geyser Basins was perfectly
transparent, and remained clear and without sediment after standing
for several years. Experiments "Showed that the silica in these
waters remained dissolved, even when the water was cooled down to
the freezing point, and it was only after the crystallization of the
water by freezing that the silica was separated and settled down as
an insoluble flocculent precipitate upon melting the ice.

How, then, are we to account for the production of the exquisite
terraces, mounds, pools and geyser cones? It has been proved, in
addition to the causes operative in the above instance, that the rapid
deposition of the sinter and travertine from both classes of water is
due to the action of vegetation in removing the carbon dioxide from
carbonated waters, thus depositing calcium carbonate, and, in the
case of the silicious waters, depositing by the activity of the proto-
plasm a gelatinous silica, which, upon exposure, finally hardens.
We know, from numerous observations, that plants are active in
rock building and disintegration.

The plants of the Carboniferous Period, by their death and con-
solidation, formed the extensive and useful coal beds. Sphagnum
and mosses compacted yield peat, and, in some cases, soft coal. Sili-
cious diatoms have given rise to extensive diatomaceous earths.
In several of the higher algae, for example, Halimeda opjintice, the
carbonate of lime deposited by the plant forms a sieve-like cover
about the tips of the algal filaments, and, in Acetabularia, it occurs
as a tube about the stalk of the plant. In the chak.e the lime is
separated and deposited in the cells and cell walls of the back alone,
while in the Corallines it is found only within the cells. Nor is our
knowledge of the activity of protoplasm in the deposit of mineral
substance solely confined to plants. We know that many animals
secrete silex and carbonate of lime, foraminifera, coral polyps and
molluscs generally. Before, however, we can understand the part
which vegetation has played in forming the travertine and sinter
beds of the Yellowstone Park, we must become familiar with the
general appearance and character of the deposits themselves.

First in importance among the many points of interest accessible
are the Hot Spring Terraces. These have been built one upon
another, until the present active portion constitutes a hill rising 300
feet above the site of the Mammoth Hot Springs Hotel. The for-

5

mation about these springs, it will be remembered, is calcareous,
and to this fact is due its distinctive character, so different from the
silica formations which prevail elsewhere in the Park. " The over-
hanging bowls which these deposits build up are among the finest
specimens of Nature's work in the world, while the water that fills
them is of that peculiar beauty to be found only in thermal springs."
Cleopatra Spring, Jupiter Terrace, Pulpit Terrace, Minerva Terrace,
are among the most interesting and beautiful of the active springs.
One of the most beautiful is a pool filled with pellucid water in vio-
lent ebullition. The sides and bottom of the basin are formed of pure
white travertine, while the varying depths cause the water to appear
all shades of blue and green, from a deep peacock blue in the deeper
parts of the bowl, to the lightest of Nile greens in the shallow re-
cesses. In wandering about the terraces, one is much impressed
with the brightly tinted basins about the springs, and the red and
orange colors of the slopes overflowed by the hot waters. These
colors are due to the presence of the microscopic plants, alga; of
several forms and species. In the cooler springs and channels simi-
lar vegetation forms the bright green, orange or brown mem-
brane-like sheets, or masses of jelly without apparent vegetal struc-
ture. Silken yellow filaments are found in bowls and channels of
the hottest springs. Words fail to convey an adequate idea of the
massive marble-like terraces, rising tier upon tier, and the exquisite
coloring of their sides and the margins of the bowls filled with
steaming hot water of most magnificent iridescent hues.

The silicious formations are similar, although not raised in ter-
races so grand or imposing, simply because the formation of silicious
sinter is much slower than the formation of the travertine, and
because the region seems to be of later geologic age. Many of the
geyser cones are bee-hive in shape, of a white adamantine-like
appearance, and are, as a rule, delicately colored by pale greens and
pinks of exquisite variation. The many hundreds of springs of the
Upper Geyser Basin, where they are seen at their best, are generally
characterized by the transparent clearness of the water, which
appears of varying shades of blue and green, according to the depth
and amount of light admitted. Morning Glory Spring is one of the
most beautiful springs of the Park, with a lunnel-sha ed cone sug-
gesting the flower, and with walls most delicately colored.

Black Sand Basin is, however, most interesting for our j:ur-

pose. The description of Dr. Peale is interestingly comprehensive,
and is as follows : " This is one of the most beautiful springs in the
Upper Basin. It has a delicate rim, with toadstool-like masses
around it. The basin slopes rather gently toward a central aperture,
that, to the eye, appears to have no bottom. The water in the
spring has a delicate turquoise tint, and as the breeze sweeps across
its surface, dispelling the steam, the effect of the ripple of the water
is very beautiful. The sloping sides are covered with a light brown
crust ; sometimes it is rather a cream color. The funnel is about
40 feet in diameter, while the entire space covered by the spring
is about 55 X 60 feet, outside the rim of which is a border of pitch
stone (obsidian) sand or gravel, sloping 25 feet. From its west
side flows a considerable stream, forming a most beautiful chan-
nel, in which the coloring presents a remarkable variety of shades ;
the extremely delicate pinks are mingled with equally delicate tints
of saffron and yellow, and here and there shades of green."

The overflow from this spring spreads out over a large area, called
Specimen Lake, where absorption of the silica from the water has
destroyed many of the trees of the vicinity, the dry, lifeless trunks
adding to the attractiveness of the place by affording the appear-
ance of petrifactions.^ All of these exquisite masses of colors which
are found lining the pools, filling the overflow channels and spread-
ing out flat in the lower marshy places, are due to the growth ot
vegetal organisms belonging to the bacteria and alg?e.

Walter H. Weed- describes the appearance of the Black Sand
Basin and channels filled with algal growths : " As the water from
this spring flows along its channel it is rapidly chilled by contact
with the air and by evaporation, and is soon cool enough to permit
the growth of the more rudimentary forms which live at the highest
temperature. These appear first in skeins of delicate white filaments
which gradually change to pale flesh-pink farther down stream. As
the water becomes cooler, this pink becomes deeper, and a bright
orange and closely adherent fuzzy growth, rarely filamentous,
appears at the border of the stream, and finally replaces the first-
mentioned forms. This merges into yellowish-green, which shades
into a rich emerald farther down, this being the common color of
fresh-water alg.x. In the quiet waters of the pools fed by this stream

^ Haynes-Guptill, Guide to Yellowstone Park, p. 68.

* Weed, Ninth Annual Report U. S. Geological Survey, p. 657.

the algae present a different development, forming leathery sheets of
tough gelatinous material, with coralloid and vase-shaped forms ris-
ing to the surface, and often filling up a large part of the pool.
Sheets of brown or green, kelpy or leathery, also line the basins of
warm springs whose temperature does not exceed 140° F., but in
springs having a higher temperature the only vegetation present
forms a velvety, golden-yellow fuzz upon the bottom and sides of the
bowl. This growth is rarelv noticed in springs where the water
exceeds 160° F., except at the edge of the pool. If the basin is
funnel-shaped, with flaring or saucer-shaped expansion, algse grow
in the cooler and shallower water of the margin, forming concentric
rings of yellow, old gold and orange, shading into salmon-red and
crimson, and this to brown at the border of the spring. Around
such springs the growth at the margin often forms a raised rim of
spongy, stiff jelly, sometimes almost rubber-like in consistency, and
red or brown in color. Evaporation of the water drawn up to the
top of such rims leaves a thin film of silica, which thickens to a crust
and so aids in the production of a permanent sinter rim."

Near some springs, for example near the Emerald Pool, algal
channels are formed and the waterway is floored with a sheet of
olive or emerald green, kelpy jelly. Where there is a moderate
current, this lining is nearly smooth, resembling a sheet of wet
leather, but in quieter waters this soft carpet is dotted with little
warty excrescences, and little pillars produced by the upward growth
of the algae; the pillars sometimes terminate by balloon-like caps
or globes containing bubbles of gas. When, by their upward
growth, these pillars reach the surface of the pool, they increase
rapidly in diameter, and form flat, cap-shaped formations which
sometimes merge into table-like expansions of quite peculiar form.
The continued growth of new pillars dams up the outlet, and the
water collecting forms shallow lagoons or pools of varying degrees
of temperature. As the temperature changes, the nature of the
growth changes, the bright-colored algous jelly forming the outer
covering of the pillars changes to light salmon-pink, and the sub-
stance itself becomes noticeably silicious, or forms a filmy web upon
the silicious centre.

It has been for some time known that the hot springs of the
world support various growths of microscopic plants. Agardh and
Corda recognized and described such in the hot springs of Carlsbad,

Bohemia. Later, Cohn, in 1862, showed that the alire of tliese
springs deposited travertine. Sir WilHam Hooker, in 1809, found
CONFERVACE^ at the borders of many of the hpt springs there. Con-
ferva limosa, C. flavescens, C. rivularis were abundant in the water.
Baring Gould, who visited the Icelandic geyser region in 1864,
found in the overflow channels of the spring, Tunguhver, a species
of the genus Hypheothrix, common in hot waters all over the world.
In New Zealand, the presence of algae in hot springs has been deter-
mined. In the hot springs of the Azores, Mr, Moseley found algae
forming a pale yellowish-green layer an inch and a half thick. The
temperature of the water was 176" F. to 194° F. A thick, brilliant
green growth, consisting of Chroococais was found at the edge of a
shallow pool of hot water, where the temperature was between
149° F. and 156° F.

In the hot springs of the Yellowstone no plant life has been found
at a temperature exceeding 185° F,, some degrees below the boil-
ing point of water, which, at the altitude of the park (7,000-8,500
feet) is 198° F. The most luxuriant growth of algae is found in
water which has cooled down to a temperature of 104° F. to 122° F.
In water of a temperature ranging from 100° F. to 125° F., we
have the greatest display of color, because many green algae can
live in nater of that degree of heat. In the hottest waters (185^ F.)
only white filamentous bacteria are found, which gradually become
of a sulphur-yellow color at 175° F. This yellow growth is due to
a species of Beggiatoa^ a plant which may be classed with the Bac-
TERiACE/E, and which, during life, deposits sulphur granules.

As the water cools down, other forms of vegetable life appear,
give variety to the colorations and give beauty to the borders
of the hot pools and overflow channels leading from them. The
sequence of temperatures and of colors is somewhat as follows:
white, 160° F.-i85° F.; yellow, 145° F.-i6o° F.; red, 130° F; green,
110° F.-i30° F,; green-orange-brown, 95° F. There are varia-
tions, however, in the sequence of these colors, owing to various
environmental conditions. Thus, in the Black Sand Basin and
Specimen Lake, the range of color is somewhat this: White, yel-
low, flesh pink, bright pink, yellowish-green, emerald.

Studying the growths at the several temperatures, we find Lcpto-
thrix lammosa growing at 135° F -185'^ F.; Phonnuiiuvi at 165° F. ;
Beggiatoa at i 50'^ F.-i65° F., and Spiru 'ni at a lovver temper, uuic

Gleocapsa, a blue-green alga, is found growing on the sides of gey-
ser cones, where steam is escaping, forming there a delicate olive-
green coloration. A kind of fibrous sinter is formed by the growth
of the little alga, Calothrix gypsophila, or the young form of Mastigo-
nema therniale, the latter olive colored, and forming the sinter of
the crater of the Excelsior Geyser.^ A coarse sinter is due to a
bright red species, Leptothrix, a finer variety to Leptothrix i^Hypheo-
thrix) lammosa, ranging in color from white to flesh pink, yellow
and red to green, as the water cools. Besides the above plants,
which belong to the Bacteriace.e and the Cyanophyce^, speak-
ing in a general way, we find that several mosses, Musci, are active
in the formation of sinter on the slopes below Hillside Spring.
These springs issue from the rhyolite slopes beneath the cliffs of
the Madison Plateau, and the waters, whose temperatures are
184° F.-I98° F., contain both silica and lime in solution, which
they deposit in their downward flow. This moss has been deter-
mined by Prof. Charles R. Barnes, of the University of Wisconsin,
to be Hypmini aduncwn, var. grasilescens, Br. and Sch.

Besides the sinter and travertine formed by algae, which remove
in the case of the carbonated waters, containing calcium bicarbonate,
Ca (HC03)2, in solution, the gaseous carbon dioxide, thus depositing
calcium carbonate, CaCOg, we have stalactites produced by the
growth of several algae, Gleocapsa violacea, Schizothrix calcicola,
Synechococcus (Eruginosus and PJiormidiiun {Leptothrix^ laniinoswn.
An interesting account of the formation of these stalactites has been
given to us by Miss Josephine Tilden, who visited, recently, the
Yellowstone Park.

In the tepid waters of the overflow basins, for example Speci-
men Lake, which is produced by the water from the Black Sand
Pool, we find extensive diatomaceous beds formed by the growth of
numerous diatoms. The water of these areas has encroached on
the timber, killing the trees, which stand as bare poles from the
treacherous marshes. It is known that these plants deposit silica,
as a box, test, or frustule, and it is thus by the activity of the proto-
plasm that the silicious diatomaceous earths are formed. Samples
of this material show the presence of Denticida valida, which forms
the bulk of the material, Denticida elegant, Navicida major, N. viri-
dis, Epithema, Cocconema, etc.

^ Weed, loc. cit.

10

It seems likely to me, in studying the vegetation of hot springs,
notwithstanding the statements of Prof. Ernst Haeckel, of Jena,
in his interesting work, " Systematische Phylogenie der Protisten und
Pflanzen," that the early forms of life on this globe were green uni-
cellular algae, and from these by retrogression and development
other forms have sprung, animal life appearing later than plant, it
seems to me, I repeat it, that we must look to the hot springs for
the most primitive forms of life, because the temperature conditions
are such as more nearly to simulate the conditions existing when
this world of ours was in a highly heated state, when seismic phe-
nomena were the rule rather than the exception. It would be neces-
sary in order to establish this proposition to investigate compara-
tively the vegetation of all the hot springs of the globe, before it
would be safe to make such a general declaration as to the origin
of vegetal life.

The above ecological sketch sufficiently discloses the salient char-
acters of the interesting geysers and hot springs of the Yellowstone
Park. In preparing this article, the writer has endeavored to give
the results of personal observation on the spot during eight days of
August, 1897, He has been materially aided in its preparation by
the following papers and books, which give a somewhat more
detailed account of the Yellowstone Wonderland:

BIBLIOGRAPHY.

1887-88, Weed. Ninth Annual Report U. S. Geological Survey, p. 619.
1895, Chittenden. The Yelloivstofie National Park, Historical afid Descrip-
tive.
1897, Haynes and Guptill. Guide to Yellowstone Park.
1897, Davis, in Science, N. S., I., p. 145 (July 30).
1897, TiLDEN, in Botanical Gazette, September, 1897.

University of Pennsylvania, November 16, 1897.

1

-~1

^

'^

I

BOSTON PUBLIC LIBRARY

3 9999 04041 362 5

Boston Public Library
Central Library, Copley Square

Division of
Reference and Research Services

\

The Date Due Card in the pocket indi-
cates the date on or before which this
book should be returned to the Library.

Please do not remove cards from this
pocket.