A New Species of Astragalus (Fabaceae) from the Wasatch Mountains of Utah

2011·3.9 MB·English

by  Beth Lowe Corbin

Madrono, Vol. 58, No. 3, pp. 185-189, 2011
A NEW SPECIES OF ASTRAGALUS (FABACEAE) FROM THE WASATCH
MOUNTAINS OF UTAH
Beth Lowe Corbin
Owyhee Field Office, Bureau of Land Management, 20 First Ave. W, Marsing, ID 83639
[email protected]
Abstract
Astragalus kelseyae B.L. Corbin, sp. nov. is described as a new species from the central Wasatch
Mountains, where it is known from only one small occurrence in Weber County, Utah. It grows in
shale talus within the Gambel oak and bigtooth maple shrubland.
Key Words: Astragalus, Fabaceae, rare plant, Utah, Wasatch Mountains.
A new species ofAstragalusis described from a elongatingin fruit. Peduncle 13-25 mm; flowering
single population in the foothills of the Wasatch axis 5-10 mm. Calyx 13-16mm long, 3.5^.5 mm
Mountains in Weber County, Utah. This distinc- wide, with narrow teeth 3^ mm long; calyx
tive milkvetch's fruit shape and texture resemble pinkish, with light and dark hairs. Petals white,
mm
some forms of A. lentiginosus Douglas ex with keel tip slightly purple. Banner 22-26
mm
Hooker, but plants differ in having a branching, long, 9—1 1 wide, bmenmtmidwayatabouta 120°
subterranean caudex, a smaller fruit beak, and angle. Wings 19-21 long, narrow, slightly
mm
generally larger (and fewer) flowers and fruit. Its cupped. Keel 18-19 long. Fruit firm,
humistrate growth form and fruit shape resemble cartilaginous, fleshy, inflated, bilocular, humi-
A. atnblytropis Barneby, but it has firmer fruits strate, sessile, with narrow and shallow dorsal
and larger flowers. Its large pods are similar to A. and ventral grooves, not curved, sometimes red
mm mm
megacarpus (Nutt.) A. Gray, and flowers and mottled. Fresh pod 35-53 long, 18-30
leaflets are similar to A. beckwithii Torr. & A. thick, 10-17 mm tall (dorsiventrally compressed),
mm
Gray, but it differs from both species by having with a small beak 3-6 long, and short,
bilocular fruit, shorter leaves, and larger flowers. dolabriform hairs. Dehiscence through the beak,
It differs significantly from each of those species after separation.
by having dolabriform (malpighian) hairs. Paratypes (topotypes): 19 May 2009 Beth Lowe
Corbin 1235 (BRY),—4 September 201 1 Beth Lowe
Taxonomic Treatment Corbin 1523 (UTC to be distributed).
Ast—ragalus kelseyae B.L. Corbin, sp. nov. (Fig. 1) Distribution and Habitat
Type: USA, Utah, Weber Co., talus slope
above Ogden, T6N, RIW, Sec 26, SLM, Astragalus kelseyae grows on the lower, west/
m
41 14'N, 111 55'W, 1625 (5340 ft) elevation, southwest-facing slope of the central Wasatch
28 May 2010, Beth Lowe Corbin 1292 (holo- Mountains, on talus openings within Quercus
type: UT; isotypes: NY, CIC, UVSC, to be ganibelii Nutt. (Gambel oak) and Acer grand-
distributed). identatuni Nutt. (bigtooth maple) shrublands.
Planta similis A. lentiginosus Douglas ex The talus consists of fine-textured Ophir shale
Hooker var. negundo S.L. Welsh & N.D. Atwood on about 50-60% slope, at about 1625 m
etA. atnblytropis Barneby in legumina biloculares elevation. This habitat is just above the old
et e var. negundo in caudices subteranneis shoreline of the Pleistocene Lake Bonneville.
elongatis et e ambo in legumina cartilagineis nec Precipitation is about 51-64 cm (20-25 inches)
chartaceis et pubescentiis dolabriformis differt. per year. The site is within the Uinta-Wasatch-
Perennial herb from branched, subterranean, Cache National Forest. Astragalus kelseyae is
woody caudex branches. Above-ground stems known only from the type locality, where about
10-20 cm long, prostrate (Fig. 2). Leaves humi- 150-200 plants were seen in a localized area of
strate, 3.0-5.2 cm long, 1.5-3.0 cm wide, with (5) about 0.1 ha. It was first found in 2009, and
7-11 (13) leaflets, the terminal jointed. Leaflets revisited in 2010 and 201 1. A popular,hiking trail
mm mm
widely elliptical, 8-15 long, 6-12 wide, bisects the occurrence, and additional undesig-
tips rounded to obtuse, more or less alternate on nated trails occur within the habitat.
the rachis. Leaves and stems silvery green with The geology of the Wasatch Mountains is a
mm
appressed dolabriform hairs about 0.5-0.8 complicated mix of sedimentary, metamorphic
mm
long. Stipules free, triangular, 4-5 long. (such as quartzite), and igneous deposits (Yonkee
Inflorescence 2-7 flowered, congested, not much and Lowe 2004). Ophir shale is a Paleozoic era
MADRONO
186 [Vol. 58
Fig. 1. Astragalus kelseyae habit, flower detail, pod cross section, and leafhair detail.
sedimentary deposit. Bands of Ophir shale and Pursh subsp. micrantha Olmstead, Asclepias
other similar talus types occur in scattered asperula (Decne.) Woodson, Apocymmi androsae-
locations across the Wasatch Front, and addi- mifolium L., Epilobium canwn (Greene) P.H.
tional occurrences ofAstragalus kelseyae may be Raven subsp. garrettii (A. Nelson) P.H. Raven,
found in the future. Hedysaruin horeale Nutt., Erysimum capitatum
The talusmicrosite is very open, with lowcover (Douglas) Greene, Eriogomtm umbellatum Torr.,
by associates, including Scutellaria angustifolia Pseudoroegneria spicata (Pursh) A. Love, Ame~
2011] CORBIN: A NEW ^^T/^^G/iLt/^ FROM UTAH 187
Fig. 2. Astragalus kelseyae in its shale talus habitat.
Icmcliier utaliensis Koehne, and Phacelia hastata bilocular fruit and dolabriform hairs. Thus, A.
Douglas ex Lehm. Although no weeds occur kelseyae differs from each ofthese species by the
directly with the Astragalus, several weedy species presence ofdolabriform hairs, and other charac-
occur in the vicinity, including Isatis tinetoria L., teristics as shown in Table 1. The new species'
Liuaria dalmatica (L.) Mill., Euphorbia niyrsiuites resemblance to A. lentiginosus is likely due to
L., and Bromus tectorum L., and pose a threat to independent parallel evolution, rather than a
this species. close relationship; the evolution ofa fruit septum
(and dolabriform hairs) does not necessarily
Relationships imply shared ancestry with other species with
these characters (J. Alexander, Utah Valley
Astragaluskelseyae appears to have similarities Univ., personal communication). Dolabriform
to A. lentiginosus, A. aiublytropis, A. luegaearpus, hairs have apparently arisen independently in
and A. beekwithii, but differs significantly from several sections within genus, but none of the
each (S. Welsh, Brigham Young Univ., personal other species with dolabriform hairs have large,
communication). Its pod resembles A. lentigino- bilocular pods, relatively few, large flowers, and
sus var. negundo with a large, bilocular fruit, but prostrate stems. The combination ofcharacteris-
differs in having a less prominent beak, generally tics present in A. kelseyae appears unique.
wider fruit, fewer flowers, a branched, subterra- Astragalus lentiginosus, with its plethora of
nean caudex, and dolabriform hairs. It is similar varieties, is widespread, including Weber Co.,
to A. aniblytropis in having a subterranean Utah; var. negundo is known from Box Elder Co.
caudex, humistrate stems, leaves, and fruit, and (which is adjacent to the north side ofWeberCo.)
somewhat similar fruit shape, but differs in and Millard and Tooele counties (southwest of
having firmer pods, larger flowers, free stipules, Weber Co.), Utah, so its range somewhat
and dolabriform hairs. It superficially appears overlaps that of A. kelseyae (Welsh 2007).
similar to A. megacarpus or A. oophorus S. Astragalus aniblytropis is limited to the vicinity
Watson with its large pods, and A. heekni'thii of Challis, in Custer and Lemhi counties, Idaho,
with its white flowers, but differs from these some 290milesnorth ofA. kelseyae(Welsh 2007).
species in the section Megacarpi by both its Astragalus niegaearpus is known from Wyoming
MADRONO
188 [Vol. 58
(at least 50 miles east ofthis occurrence), central
Utah (about 120 miles south), Nevada, and
S o Colorado, while A. beckwithii occurs in Weber
W o Is.. Co. and generally to the west in Utah, and in
co 2^._S2 I -o 3c« ri C ^—O^« r^i^jn C(cU3 «c« CSIhdouallhutomz,bNieeatva(adAl.alb,e2Oe0r1ee0t;goanlU.,S1WD9a8sA8h;inW2g0et1l0os)nh.,eaAtnsdatlr.Barg2ia0tl0i8us;sh
P u c ' ^ IT) oBaospihno,ruesasotcciunrtso wmeossttelryniCnoltohreadsoo,uthbeurtnisGraelasto
X5 -d recorded from northwest Utah (Box Elder and
USDA
Tooelecounties) (Welsh et al. 2008; 2010).
o S u 7 (U !^ c/5 C Thus,thelocationofA. kelseyaeisattheeastedge
ofthe ranges ofA. lentiginosiis var. negundo and
o^ OON g - o^ O ^ rv A. hecknithii, close to the northern edge of the
oj O 1, I §7 driasnjguensctoffrAo.m mA.egaamcbalryptruospiasn.d A. oophorus, and
Astragalus kelseyae is named in honor ofAnn
Kelsey, plant collection manager for the Univer-
y .1 f\ sity ofUtah, with whom I've spent manypleasant
field days in the mountains and deserts of Utah.
CD S2 This plant is of conservation concern because
I only one occurrence with few individuals is
^O r^i ^7 known, and because potential threats exist from
3^ IE trails and invasive weeds.
"B. ^ 00 I
a;d CC >X^ 0^0 ^c; Key to Similar Species
2 c^ IT[) (adapted from Barneby 1989 and Welsh 2007)
1. Hairsdolabriform; pods fullybilocular . . .A. kelseyae
^ r. Hairs basifixed; pods unilocular or bilocular
00
O <u ^ ri 2. Pods unilocular
<U ~i r-' bb-5 3. Pod 1.5-3.7cmlong,valvesleatAh.erhye.ck.wi.tliii
3'. Pod (2) 3-6 (7.5) cm long, valves papery
C/5 g C o-—•iCnJ a(./>3. 4. P5lcanmtslosnugbacaulescent, As.temmesga1e-arpus
4'. Plants caulescent, stems mostly 5-
C3 .5 -O Xi 00 20 cm long A. oophorus
2'. Pods bilocular
I5f)f-82^ 5. tSteirprualneesanconnate; caudex deAe.playmbsluybt-ropis
>
5'. Stipules free; caudex superficial (near
O Da o ^ soil surface) A. lentigiuosus
ri ri
ONi X O I (L) <U C Acknowledgments
c 4^7m ^ I thank Stanley Welsh (Brigham Young University,
CJ 15 S "55 c3 BRY) for detailed information, the Latin diagnosis, and
access to the herbarium. I also thank Stephen Clark
(Weber State University, WSCO), Don Mansfield
O (College of Idaho, CIC), Michael Piep (Utah State
ri c o University, UTC) and Ann Kelsey (University ofUtah,
oI UT) for access to collections. Jason Alexander (Utah
T3i C Valley University) provided helpful comments and
,o g in insights. Dan Scott produced the illustration, which was
tj-j cC dS C funded by the Intemiountain Region ofthe U.S. Forest
iS S rI 13 S Service, thanks to Teresa Prendusi, who also reviewed a
'o 5 I draftofthisarticle,asdidDonMansfield.Thispaperwas
also improved by reviews from Stanley Welsh and Leila
Shultz; however, any mistakes are all mine.
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