PACKERA MANCOSANA (ASTERACEAE: SENECIONEAE),
A NEW SPECIES AND SHALE BARREN ENDEMIC OF SOUTHWESTERN COLORADO
LORAINE YEATTS
1395 Nile Street
Golden, Colorado 80401
Adjunct Researcher
Kathryn Kalmbach Herbarium
Denver Botanic Gardens
Betty and Al Schneider
19049 Road V
Lewis, Colorado 81327
ABSTRACT
Packera mancosana L. Yeatts, B. Schneider, & A Schneider, sp. nov., is described from
outcrops of grayish, argillaceous marine Mancos Shale in southwestern Colorado. The new species is
currently known from several small populations in and adjacent to Lone Mesa State Park in Dolores
County, Colorado, where it is represented by several hundred plants. The plants are most closely
allied with the Tomentosi subgroup of the Aureoid senecios but are sufficiently different
morphologically and isolated geographically from those species to be considered a distinct species.
KEY WORDS: Packera, Senecioneae, Mancos Shale endemic, Colorado
Biological exploration of Lone Mesa State Park in Dolores County, Colorado has brought to
light a previously unknown species of Packera. It was first encountered in June 2008 by Betty and
Al Schneider during floristic surveys of Lone Mesa State Park.
The new Packera exhibits salient features of the Tomentosi subgroup of the Aureoid senecios
(Barkley 1988), which includes P. cana (Hook.) W.A. Weber & A. Love, P. werneriifolia (A. Gray)
W. A Weber & A Love, P. spellenbergii (T.M. Barkley) C. Jeffrey (Barkley 1980; Jeffrey 1992), and
Senecio cliffordiiN.D. Atwood& S.L. Welsh (Welsh et al 2003). This group is characterized by
creq^ing rootstocks or stout caudices with fibrous roots, basal leaves well-developed and entire to
shallowly lobed, cauline leaves progressively to abruptly reduced upward or all bracteate, leaf
margins with few or no callous denticles, and some tomentum usually persistent and evident even in
age.
Packera mancosana L. Yeatts, B. Schneider, & A Schneider, sp. nov. Figs. 1-5. TYPE: USA.
Colorado. Dolores Co.: Lone Mesa State Park, S end of the park, ca. 23 mi N of the town of
Dolores, T39N, R14 W, Section 35, ca. 108" 28W, 37" 41'N, exposure of Mancos shale, ca.
2% slope, 7575 ft; with dominants Helianthetta microcephala, Physaria pulvinata,
Tetraneuris acaulis, Townsendia leptotes, and Eriogonum lonchophyllum, abundant
Gutierrezia elegans, Petradciria pumila, Astragalus missouriensis var. amphibolus, and
Heterotheca villosa, scattered Calochortus nuttallii, Delphinium nuttallianum, Orthocarpus
purpureoalbus, Packera oodes, Solidago simplex, and others; Pima ponderosa with pinyon-
juniper on nearby surrounding slopes; dense leafy mounds, flowers yellow; 26 May 2009, Al
Schneider 5077 with Betty Schneider (holotype: KHD; isotypes: COLO. MO. NY, RM US).
Packerae werneriifoliae similis capitulis radiatis, laminis ellipticis foliorum, et pedunculis
bracteatis sed differ! cypselis majoribus pubescentibus et habitationibus argillae calcarei ad altitudines
Yeatts, Schneider, and Schneider: Packera
timenti laminarum foliorum sed
, caulinibus abrupte deminutis,
recessas. Packerae canae similis capitulis radiatis et formae a
differt caulinis brevionbus, phyllarns minus pubescentibus,
flosculis disci brevioribus, et cypselis pubescentibus.
Perennials, caespitose in dense tufted mats to 30 cm in diameter and 3 cm high, from
creeping or suberect rhizomes, with stout branched caudices up to 7 mm thick at junctions; roots
fleshy-fibrous. Stems 1 per rosette, (5.2-)7-10(-13.3) cm high, simple or 1-2-branched near
midstem, lanate woolly when young, becoming floccose to rarely glabrate distally at anthesis,
bracteate. Basal leaves petiolate, petiole dilated at base and axils obscured by white lanate
tomentum, blades oblanceolate or narrowly elliptic, 29-34 mm long, 3-6 mm wide, thick, leathery, ±
succulent; lanate on both surfaces, sometimes becoming floccose (rarely glabrate) in age, margins
usually ± revolute, especially proximally, sometimes plane, ± thickened, ± cyanic, acute, entire with a
denticle at the acute apex or apically shallowly tndentate. Cauline leaves 3 (-5), sessile, linear-
lanceolate, 2-5 mm long, 0.1-0.01 mm wide, usually cyanic distally typically with lanate, floccose
dorsal surface and floccose to glabrate, mammilate ventral surface. Heads solitary or 2(-3) in loosely
subcorymboid arrays. Calyculi conspicuous, scarious, glabrate, less than 1/3 lengths of phyllaries.
Phyllaries 15 or mostly 21 on larger heads, (5-)7-9(-10) mm long, ensiform, equal, green to cyanic,
usually scarious-chartaceous and ciliate— floccose margined, floccose dorsally, erose and ciliate to
tufted near apex. Ray florets mostly 5-8(-ll), averaging 7 per head, corolla laminae 5-7 mm long,
tube 3.7-4.2 mm long. Disc florets ± 34, 5. 1-7.0 mm long, tube 1 .7-2.0 mm long. Cypselae 3. 1^1.0
mm long, with 4-5 thickened, green, short-pubescent ridges, intervals glabrous; pappus 4.7-5.2 mm
long, capillary bristles white, nearly as long as disc floret. Chromosome number unknown.
Measurements for achenes and florets are from rehydra
description generally matches those in Trock (2006).
I corollas. The format of the
Additional collection. USA. Colorado. Dolores Co.: 7.5 ? Willow Spring quad quad, NAD27 12S
0722314E 4173556N, Lone Mesa State Park along San Juan Nad. Forest Rd 514 ca. 0.3 mi W of
Plateau Creek, 0.15 mi N of S entrance to Park; 7588 ft; Mancos Shale; almost flat area on barren
desert pavement of broken calcareous chips, clayey soil and rock crevices; ca. 50% vegetated with
.Artemisia nova, Helianthella microcephala, Orthocarpus sp., Townsendia leptoies, grasses and other
spp.: plants rhizomatous, forming dense mats up to 1 ft., in diam., just beginning growth; leaves gray-
green, tomentose-cobwebby, heads just appearing; ray and disc flowers yellow, locally common but
not seen elswhere in Lone Mesa State Park, 26 Apr 2009, Loraine Yeatts 5733 with Al & Betty
Schneider and Dick Yeatts (COLO, KHD, RM, and others to be distributed). This collection (Fig. 5)
is essentially from the same population as the holotype but collected one month earlier.
State Park, type locality.
s, Szhnelder, and Szhnelder : Paok&3
Etymology. The specific epithet "mancosana" alludes to ihe soils on which the species is found The
name "Mancos Shale" is detived from the town of Mancos in southwest Colorado where this shale
formation is abundant. Common name: Mancos Shale Packera
Packero. mancosana is known from several small populations that overlap the southern
boundary of Lone Mesa State Park. The type locality is within the Park Two othet recently
described species. Physaria pulvinata (OKane & Reveal 2006) and Gulierrezia elegans (Schneider et
ai. 2008), grow immediately adjacent to and in close proximity to Packera mancosana.
Figure 3. Packera mancosana at the type locality — growth habit.
: Packera mancosana 5
Packera mancosana is distinguished from its closest relatives by the contrasts indicated in the
key below. Information on related species is from the Intermountain Flora (Cronquist 1994), FN A
treatment of the Tomentosi subgroup in (Trock 2006), A Utah Flora (Welsh et al. 2008), and the New
Mexico Rare Plants website (NMRPTC 2010).
KEY TO SPECIES
1. Heads usually eradiate (rays sometimes 5-8 in P. spellenbergii); basal leaves sessile and linear to
linear-oblanceolate, margins usually strongly revolute; cypselae pubescent on ribs.
2. Basal leaves (blades) 10-15+ x 1-2 mm; phyllaries usually 13; stems 1-2 per rosette; New
Mexico (Harding and Union cos.) Packera spellenbergii
2. Basal leaves (blades) 20^10 mm x (l-)2-3 mm wide; phyllaries 13 to mostly 18; stems l(-2)
per rosette; New Mexico (McKinley and Rio Arriba cos.), Arizona (Apache Co.), Utah (Kane Co.)
Senecio cliffordii
1. Heads radiate (ra3's rarely in P. werneriifolia); basal leaves usually petioiate with mostly elliptic
to lanceolate blades, margins plane or slightly revolute; cypselae completely glabrous or pubescent on
3. Cauline leaves gradually reduced distally; stems 1 per rosette; heads 8-15+ in corymbiform
arrays; cypselae 2.5-3.5 mm long Packera caiia
3. Cauline leaves abruptly reduced distally, bractlike and inconspicuous; stems 1-5 or 1 per
rosette; heads l-5(-8) per stem; cypselae 1.5-2 mm or 3.1-4 mm long.
4. Leaves glabrous to glabrate at maturity, dark green, glossy; blade margins usually shallowly
serrate-dentate; stems 1-5 per rosette; heads l-5(-8) per stem; cypselae 1.5-2 mm long,
completely glabrous Packera werneriifolia
4. Leaves persistently tomentose, gray-green, dull, blade margins entire or apically shallowly
tridentate; stems 1 per rosette; heads l-2(-3) per stem; cypselae 3.1-4 mm long, pubescent on
ribs Packera mancosana
Packera werneriifolia as described by Trock (2006) is morphologically variable over its
range. Leaves vary from spatulate with ovate, elliptic, or narrowly elliptic blades and flat, dentate
margins in the Rockies to narrowly obianceolate to oblong-oblanceolate and essentially epetiolate
with revolute, mostly entire margins in California and Arizona (see photos on Calflora 201 1). Far-
western populations also tend to be more persistently tomentose than the Rocky Mountain ones. The
key contrasts above are for Rocky Mountain plants.
The distinction between Packera mancosana and P. werneriifolia appears to be discontinous
both in morphology and ecology and recognition of P. mancosana at specific rank is appropriate.
Packera mancosana is more similar in leaf morphology to far-western expressions of/', werneriifolia
than to Colorado ones but this similarity apparently is convergent.
Habitat The new species is represented by a total of over 400 plants at the type locality. The plants
occur as well-separated individuals on very sparsely vegetated flats (slopes ca. 2%) and sides of
shallow washes. They grow along cracks in the bare shale and in thin gravelly soil over the shale.
Packera mancosana is among the more abundant species in this habitat. Depending on the arrival of
spring, it begins flowering in mid-May, fruiting into July.
-ogafSl
:osana in Lone Mesa State Park, type locality.
Figure 4. Habitat of Packera mc
Further exploration will be needed to determine if there are additional populations of Packera
mancosana and to determine if this species is restricted to Mancos Shale. Herbarium records studied
indicate that none of the other closely related Packera species in the Tomentosi subgroup have been
documented on Mancos Shale. Several yet unaccessioned collections of Packera cana at RM (Rocky
Mountain Herbarium 2011) were collected on Cretaceous Pierre Shale, which probably is not
calcareous but which correlates in time with Mancos Shale.
In growth habit and substrate preference Packera mancosana is most similar to P.
spellenbergii and Senecio cliffordii, which form tufted mats on limey substrates. Senecio cliffordii
was treated as a synonym of P. spellenbergii by Trock (2006), but Trock has now agreed with
regional botanists who conclude that the two are distinct (NMRPTC 2010).
Packera cana is the most cosmopolitan of the group in its ecological requirements, flowering
by the middle of May at low elevations (to 200 m) and much later in August at alpine altitudes (to
3700 m) on a variety of substrates. Packera werneriifolia is primarily found near and above treeline,
occasionally lower. Of the 121 Colorado specimens of P. werneriifolia housed at University of
Colorado Museum (CU Museum-COLO 201 1), only 13 were located below 9000 feet in elevation.
Yeatts, Schneider, and Schneider: Packera mancosana 7
Figure 5. Large mat of Packera mancosana, engulfing a plant of Townsendia leptotes. On the
Mancos Shale it is common for plants to grow in close association — the first-established providing a
microhabitat similar to a nurse-log.
ACKNOWLEDGEMENTS
We are grateful to Scott Elder (Superintendent of Lone Mesa State Park) for his cooperation,
Stanley Welsh (BRY) for studying our specimens and suggesting that we describe this Packera as a
new species, Tim Hogan (COLO) for access to Packera specimens for study and measurements,
Arnold Clifford for his inspiring understanding of the Four Corners geology and floristics and the
opportunity to view his personal Senecio cliffordii type specimen for comparison study, and to Chick
Keller and Craig Freeman for helpful review comments. We are especially grateful to Guy Nesom
for expeditiously providing suggestions, editorial assistance, and the Latin translation. Photographs
are by the authors; also see Schneider (201 1) for others.
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States. Phytologia 67: 237-253.
: Packera mancosana 8
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