Pediomelum Rydberg (Leguminosae) in Arizona and Two Previously Undescribed Species
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Western North American Naturalist Volume 70 Number 1 Article 2 4-13-2010 Pediomelum Rydberg (Leguminosae) in Arizona and two previously undescribed species Stanley L. Welsh Brigham Young University Max Licher Botanist-Architect, Sedona, Arizona Follow this and additional works at: https://scholarsarchive.byu.edu/wnan Recommended Citation Welsh, Stanley L. and Licher, Max (2010) "Pediomelum Rydberg (Leguminosae) in Arizona and two previously undescribed species," Western North American Naturalist: Vol. 70 : No. 1 , Article 2. Available at: https://scholarsarchive.byu.edu/wnan/vol70/iss1/2 This Article is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Western North American Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. Western North American Naturalist 70(1), © 2010, pp. 9–18 PEDIOMELUM RYDBERG (LEGUMINOSAE) IN ARIZONA AND TWO PREVIOUSLY UNDESCRIBED SPECIES Stanley L. Welsh1 and Max Licher2 ABSTRACT.—Examination of specimens of Pediomelum in the Brigham Young University Stanley L. Welsh Herbarium (BRY), and others obtained on loan from the Northern Arizona University Deaver Herbarium (ASC), the Arizona State University Herbarium (ASU), and the University of Arizona Herbarium (ARIZ), allows for substantial reevaluations of the species in Arizona and for description of 2 previously undescribed species. Pediomelum verdiensis S.L. Welsh and M. Licher is described as a new species from substrate derived from the Tertiary Verde Formation, Verde Valley, north central Arizona. Pediomelum pauperitense S.L. Welsh, M. Licher, and N.D. Atwood is described as a new species from outcrops of Paleozoic limestone near Poverty Mountain, Coconino County, Arizona, north of the Grand Canyon. For the species of Pediomelum in Arizona, we include a summary revision, a key to the taxa, and a list of specimens examined for study. Key words: Pediomelum, new taxa, summary revision, Arizona flora. The genus Pediomelum was erected by P.A. P. megalanthum. The smaller, purple-bannered Rydberg (1919) to accommodate those plants plants clearly do not fit within that concept. from North America previously known under Grimes (1990), in his summary monograph the collective heading Psoralea L. (Linnaeus of New World Psoraleae, limits the concept of 1753). The type material for Psoralea came from P. megalanthum, sensu lato—including vars. Africa; and in a strict sense, Psoralea consists of megalanthum, retrorsum, and epipsilum (herein a dozen or more species of South African shrubs treated at specific rank)—to those materials or small trees. Their relationship to North having the calyx tube at least 6 (actually 5–6.5) American materials has been discounted not mm long and upper calyx teeth lanceolate. He only by Rydberg but also by other workers in included among the species having calyx tubes the Leguminosae, tribe Psoraleae (Barneby shorter than 6 mm (2–4.5 mm), the geographi- 1989, Isely 1998, Welsh et al. 2008). cally disjunct P. pariense (S.L. Welsh & N.D. Attention to species of Pediomelum Ryd- Atwood) Grimes and P. californicum (S. Wat- berg in Arizona was stimulated when photos son) Rydberg, and the Arizona species P. and specimens of 2 distinctive acaulescent to mephiticum (S. Watson) Rydberg. The first of short-caulescent species of the genus were these, P. p a r i e n s e , occurs mainly on Tertiary received from coauthor Max Licher. The plants Claron and Jurassic Carmel limestone forma- differ markedly from each other in floral char- tions in central to western Kane County, Utah; acteristics. One is large-flowered (11–15 mm) P. californicum is known from southern Califor- with white banners and with most calyx tubes nia and northern Baja California, Mexico; and exceeding 6 mm, the length indicated by P. mephiticum is known mainly from northern Grimes (1990) for Pediomelum megalanthum. Mohave County, Arizona, north of the Grand Specimens of that species from throughout its Canyon, and from southwestern Washington range had calyx tube lengths of 5.0–6.5 mm. County, Utah. Pedio melum mephiticum extends The other plant sent by Licher had smaller south of the Grand Canyon to the vicinity of flowers (9.8) 10–11.3 mm with blue-purple or Wikieup, Arizona. purple banners and calyx tubes (3) 3.5–4.8 mm in length. Identification of both the large- and METHODS small-flowered plant specimens was attempted following Grimes (1990). The larger, white-ban- A list of specimens from Arizona that we nered plants clearly fit within the concept of examined and cite appears in the Appendix. 1Emeritus Professor and Curator, Stanley L. Welsh Herbarium, Brigham Young University, Provo, UT 84602. 2Botanist-Architect, Box 1456, Sedona, AZ 86339. 9 10 WESTERN NORTH AMERICAN NATURALIST [Volume 70 Fig. 1. Distribution map of Arizona species of Pediomelum. This study is based not only on specimens Arizona. Three sheets of the acaulescent P. of Pediomelum at the Brigham Young Univer- pentaphyllum (L.) Grimes were examined, all sity Stanley L. Welsh Herbarium (BRY) but from Greenlee and adjacent Cochise counties, also on others obtained on loan from the North - Arizona; and one sheet was examined of the ern Arizona University Deaver Herbarium short-caulescent P. palmeri (Ockendon) Grimes (ASC), the Arizona State University Herbarium from Santa Cruz County, Arizona. Specimens (ASU), and the University of Arizona Herbar- from throughout Arizona (all from populations ium (ARIZ). The majority of sheets examined adjacent to the Nevada border in Mohave of P. epipsilum (Barneby) S.L. Welsh were from County) and Nevada were examined for P. c a s - Utah; only 2 were from Arizona, both on the toreum (S. Watson) Rydberg. Triassic Moenkopi Formation west of Fredo- nia. Specimens from throughout the distribu- RESULTS tion of P. megalanthum were examined, but only those from Arizona and New Mexico are Review of specimens examined for this cited. Those of P. retrorsum Rydberg were study confirmed the presence of 10 species of examined also, the majority of which were from Pediomelum in Arizona. Examination also 2010] PEDIOMELUM IN ARIZONA 11 confirmed the distinct nature of the small-flow- 4. Calyx lobes very unequal, the lower one much ered materials with ascending hairs on pedicels enlarged or much differing in shape from the narrowly subulate upper ones; seeds reticulate and peduncles from the Verde Limestone For - or rugose . 5 mation. This examination also demonstrated — Calyx lobes subequal to moderately unequal, the existence of a second set of small-flowered the lower one not-much enlarged; seeds plants with ascending hairs on both pedicels smooth . 6 and peduncles from north of the Grand Canyon in the vicinity of Poverty Mountain. 5. Calyx tube 3–4 mm long; lower calyx lobe The specimens from the Verde Limestone For- rounded or obtuse at the apex, ca. 10 mm long; plant known from NW Mohave Co., Arizona, mation apparently bear flowers with all petals Clark Co., Nevada, and San Ber nar dinoCo., more or less suffused with dark purple or California, often growing in sand . blue-purple. Those from the Poverty Mountain . P. castoreum (S. Watson) Rydberg area are pale-flowered and the leaves tend to — Calyx tube 4–5 mm long; lower calyx lobe greatly overtop the inflorescences. Both the acute to attenuate at apex, ca. 12–15 mm Verde Limestone and the Poverty Mountain long; plants known from Cochise Co., Arizona, adjacent New Mexico and Mexico . plants are described and named below. N.D. P. pentaphyllum (L.) Grimes Atwood provided insight into habitat and growth of the novelty described below from the 6. Calyx tube mainly 5.0–6.5 mm long; flowers vicinity of Poverty Mountain in northern Ari- 11–15 mm long . 7 zona. He is thoroughly familiar with the plant — Calyx tube mainly 2.5–4.5 mm long; flowers in its habitat and has collected it previously. 7.3–13.5 mm long; plants of north central Ari- Species of the genus Pediomelum, as they zona and SW Utah. 8 occur in Arizona, are mainly geographically 7. Petioles and peduncles with hairs appressed or discrete from each other; that is, the distribu- appressed ascending, sometimes with a few tions still occupy discrete habitats within areas long spreading hairs; plants of Apache Co. and of apparent overlap (Fig. 1). disjunct in S Coconino and adjacent Yavapai cos., Arizona, NW New Mexico, W Colorado, and E Utah. TAXONOMY . P. megalanthum (Wooton & Standley) Rydberg — Petioles and peduncles with retrorse or retrorse- The following key will serve to delimit the spreading hairs; plants of Coconino, Graham, species of Pediomelum that are known to occur Gila, Maricopa, Mohave, and Yavapai cos., Ari- in Arizona: zona, Clark, Lincoln, and Nye cos., Nevada, and Washington Co., Utah . P. retrorsum Rydberg 1. Leaflets conspicuously bicolored, cinereous beneath, bright green and glabrous to glabrate 8. Petioles and peduncles both retrorsely hairy; above (except along some veins); plants only lateral and upper calyx teeth narrowly subu- known from the Triassic Moenkopi Formation late to narrowly elliptic; plants of various from SW Kane Co., Utah, and N Coconino Co., substrates in N Mohave Co., Arizona, N of Arizona. P. epipsilum (Barneby) S.L. Welsh Grand Canyon, extending S to Wickiup, and Washington Co., Utah. — Leaflets mainly greenish on both sides, or if . P. mephiticum (S. Watson) Rydberg contrasting, pale beneath and green above, the upper surface also strigose to pilose. 2 — Petioles with hairs appressed ascending or ascending; pedun cles ascending- to spreading- hairy; lateral and upper calyx teeth lance-elliptic 2. Plants definitely caulescent; leaflets green on to lance-subulate or narrowly oblanceolate to both sides; flowers mainly <10 mm long. 3 oblong-attenuate . 9 — Plants acaulescent or short-caulescent; leaflets typically pale beneath; flowers mostly >10 9.