Research Article |
Corresponding author: Christopher Lee ( chris.lee@monash.edu ) Academic editor: Alexander Sukhorukov
© 2022 Christopher Lee, Curtis R. Björk, Jeannette Whitton.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Lee C, Björk CR, Whitton J (2022) Townsendia lemhiensis (Asteraceae, Astereae): A narrowly endemic new species from Idaho, USA. PhytoKeys 193: 67-75. https://doi.org/10.3897/phytokeys.193.76365
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Townsendia lemhiensis (Asteraceae) is described from the Lemhi Valley of east-central Idaho. From a genus with weak intrinsic isolating barriers, T. lemhiensis remains distinct apparently due to apomixis and to its isolation and habitat specialization on spatially limited occurrences of ashy white soils in the Lemhi Valley. Despite similarities to T. spathulata, this new species differs in its persistent pappus, fewer series of phyllaries and sericeous rather than long woolly hairs.
Apomixis, compositae, Flora of Idaho, Lemhi Valley
Townsendia Hook. includes about 29 recognized species distributed predominantly throughout the Rocky Mountain and Great Basin regions of western North America (
Specimens were initially collected during cursory exploration by Curtis Björk on May 20th, 2012. Curtis Björk further sampled the area in 2013, and two additional populations were found. In 2018, Chris Lee and Jeannette Whitton used localities provided by Curtis Björk to collect additional samples. We also used satellite imagery of nearby areas to identify potential habitat for T. lemhiensis, and these areas were targeted for additional surveying. Several voucher specimens were taken during each site visit, and dried between newspaper and cushioned cardboard in a plant press. Characters were measured directly from herbarium specimens. Herbaria acronyms follow Index Herbariorum (
We removed 2–3 florets from individual plants and placed them in a 200 μL microtube. After adding approximately 20 μL of lactophenol blue stain to each tube, we vortexed tubes for 20–30 seconds to release pollen into suspension. Slides were prepared using the resulting suspension, and viewed under a standard light microscope. This procedure was repeated multiple times on various specimens but yielded no pollen grains, thus no pollen counts or measurements could be completed. We later examined disk florets from individuals of all known populations under a dissecting microscope, and found that stamens were abortive and evidently non-functional; no anthers were observed.
Björk 29248 (UBC V252324) 20 May 2012. USA, Idaho, Lemhi County, 18 Mile Wilderness Area, ca. 24 km SSE of Leadore, 44.44806°N, 113.17222°W, on dry ashy white soil on slope (7368 ft) in sagebrush steppe (Fig.
Ab Townsendia spathulata pappi ad maturitatem persistens, series phyllariorum pauciores, pilis caulibus sericeus non villosus, folia non carnosa differt.
Plants perennial, 25–30 mm tall, rosette forming, rosettes 8–17 mm wide, solitary or (more often) arising from a few-branched caudex; stems essentially absent, or when visible, then villosulous; leaves 4–14 × 2 mm, narrowly oblanceolate to narrowly elliptic-oblanceolate, silvery, moderately sericeous but not villous, apex acute; capitula one per fertile rosette, sessile or nearly so; involucre campanulate, 9–10 mm wide, phyllaries appressed, narrowly elliptic-lanceolate, 6–7 × 1 mm, graduated, in 2–3 series, reddish brown, sericeous, apex acute to acuminate; ray florets 15–24, pistillate; ray corollas true ray, 7–8 mm long, surpassing pappus bristles, light brownish pink or whitish and tipped in pink, slightly darker abaxially, aglandular; disc florets 24–30, functionally pistillate; disc corollas tubular, 4 mm long, shortly surpassed by the pappus bristles, yellow, aglandular; stamens reduced to strap-like staminodes, anthers and pollen absent; cypselae 3 × 1 mm, oblanceolate and compressed, with glochidiate hairs; pappus bristles 23–26 in disc florets, 14–20 in ray florets, 6–7 mm long, white, barbellate, persistent. (Figs
Townsendia lemhiensis is named after the Lemhi Valley, Idaho, where individuals of this species were first noticed by Curtis Björk.
Townsendia lemhiensis is known only from the Lemhi Valley in east-central Idaho, which is situated within a region known for its numerous geographically endemic plants (
Townsendia lemhiensis grows on ashy white slopes of eroded rhyolite tuff. These slopes of powdery soils and friable rock are sparsely vegetated, forming edaphic islands of open ground within a more densely vegetated surrounding matrix of sagebrush steppe. Numerous other plants having narrow geographical ranges occupy similar ashy slopes elsewhere in dry interior regions of western North America (
Associated species growing with Townsendia lemhiensis on the ashy slopes include: Artemisia frigida Willd., 1838, Artemisia tridentata subsp. wyomingensis Beetle & A.L.Young, 1965, Chaenactis douglasii Hook. & Arn., 1839, Comandra pallida A.DC., 1857, Cymopterus bipinnatus S.Wats., 1885, Elymus lanceolatus (Scribn. and J.G.Sm.) Gould, 1949, Eriogonum mancum Rydb., 1917, Eriogonum soliceps Reveal & Björk, 2004, Ipomopsis spicata subsp. orchidacea (Brand) D.Wilken & R.L.Hartm., 1991, Linum lewisii var. alpicola Jeps., 1936, Oreocarya humilis Greene, 1896, Packera cana (Hook.) W.A.Weber & Á.Löve, 1981, Penstemon humilis Nutt. ex A.Gray, 1862, Phlox muscoides Nutt., 1831, Stenotus acaulis (Nutt.) Nutt., 1840, Townsendia hookeri Beaman, 1957, T. leptotes (A.Gray) Osterh., 1908, and T. parryi D.C.Eaton, 1874.
We observed T. lemhiensis in flower in mid-May over three years (2012, 2013, 2018). At this time, some individuals had some capitula in bud, and others had mature seeds or open flowers. On this basis, we describe flowering as likely occurring throughout May, and seedset through late May or possibly into June. Further studies are needed to document the timing of bud formation, and potential variation in flowering and fruiting phenology. Another early-flowering species, Townsendia hookeri, co-occurs with T. lemhiensis, and has been observed to set buds in fall that open soon after snow melt (Lee and Whitton, personal observation). Given the early flowering of T. lemhiensis and the presence of snow patches persisting in surrounding areas, we suspect fall bud set may also occur in this species. Co-occurring species of Townsendia were found on site in bud (T. parryi) and late-bud (T. leptotes and T. hookeri).
Townsendia lemhiensis is most similar in morphology to T. spathulata Nutt., which shares a generally hairy appearance. However, T. lemhiensis is morphologically distinct because its leaves are narrowly oblanceolate with short dense pubescence, instead of the fleshy, spathulate leaves covered in long, tangled hairs in T. spathulata. Also, the cypselae of T. lemhiensis have persistent pappi rather than the rare characteristic (in Townsendia) of deciduous pappi found only in T. spathulata, T. microcephala and T. condensata (
Townsendia lemhiensis is morphologically distinct from the seven other species of Townsendia known from this region. We include T. spathulata here, because of its similarity to T. lemhiensis, and because it has been documented in the Beaverhead range overlooking the Lemhi Valley, Idaho (>9000 ft) at the border with Montana (Fig.
Although many Townsendia species occupy distinct geographical ranges and possess a multitude of unique character traits,
Although direct genetic or experimental evidence of apomixis is not available for T. lemhiensis, no pollen was detected on florets sampled from our collections, which strongly suggests that these populations are apomictic. As a result, despite the physical proximity of T. lemhiensis to T. hookeri, T. leptotes, and T. parryi, hybridization is unlikely given that in this region, all four species are likely apomicts (
The first author examined the majority of Townsendia specimens from UBC, UAC, SASK, RM, CS, and UNLV from 2008–2014, and the second author examined all Asteraceae at ID in 2002, and did not find any specimens of Townsendia lemhiensis. Additionally, from 2008–2014, the first author undertook targeted searches for all species of Townsendia throughout their range in WA, ID, MT, WY, CO, NV, NM and CA, and no similar populations were encountered.
Despite the second author’s searches in apparently suitable habitats throughout the Lemhi Valley and adjacent valleys in Idaho and Montana in the years 1999–2013, only the three reported populations have been located. Thus it appears that T. lemhiensis is a high priority for conservation. All known occurrences of T. lemhiensis are situated on public land administered by the Bureau of Land Management. Hence, the landscape surrounding this species is somewhat protected from threats, but such a small, rare species may still undergo population reduction from factors such as trampling by cattle or recreationists, invasive exotic plant species, or from climate change that could cause higher frequency and severity of drought and excessive heat events.
1a | Lax-growing plants with elongated stems, many internodes > 2 mm long, plants often lacking sterile rosettes when flowering | 2 |
2a | Stems erect or sub-erect; longest phyllaries > 9 mm long | 3 |
3a | Rays purplish; longest phyllaries mostly > 10 mm long; stems erect, unbranched | T. parryi |
3b | Rays white or pink; longest phyllaries mostly < 10 mm long; stems sub-erect, often branched | T. florifera |
2b | Stems decumbent; longest phyllaries up to 9 mm long | 4 |
4a | Stems gray-white, obscured by dense hairs | T. incana |
4b | Stems lightly to moderately strigose | T. strigosa |
1b | Compact plants, stems scarcely elongated, internodes < 2 mm long; sterile rosettes commonly present | 5 |
5a | Plants with abundant spreading hairs | 6 |
6a | Pappus persistent; leaf hairs sericeous | T. lemhiensis |
6b | Pappus easily breaking away from the cypselae at maturity; leaf hairs villous | 7 |
7a | Phyllaries > 40, the longest ones > 9 mm long, involucres > 12 mm long | T. condensata |
7b | Phyllaries < 40, the longest ones < 9 mm long, involucres < 12 mm long | T. spathulata |
5b | Plants with appressed hairs only, or spreading hairs few and inconspicuous | 8 |
8a | Phyllaries 2–5 × long as wide; rays purplish, often glandular abaxially | 9 |
9a | Phyllaries acute to acuminate; ray laminae 5–8 mm long | T. leptotes |
9b | Phyllaries blunt; ray laminae 7–16 mm long | T. montana |
8b | Phyllaries at least 6 × long as wide; rays white to pink, glabrous | 10 |
10a | Longest phyllaries > 12 mm long and > 1.5 mm wide; disc pappi 6.5–11+ mm long; leaf midvein apparent | T. exscapa |
10b | Longest phyllaries < 12 mm long and ca. 1 mm wide; disc pappi 4–6(-7.5) mm long; leaf midvein obscure | T. hookeri |
We are grateful to Ryan Batten for his assistance in the field. The curatorial staff of UBC, CS, ID, RM, SASK, UAC, and UNLV are thanked for their kind and generous help facilitating specimen research. In particular, we appreciate the rapid assistance from Linda Jennings and Spencer Goyette at UBC in processing accession numbers, and mounting, photographing and scanning specimens for this study.
Townsendia lemhiensis occurence records
Data type: Occurence.
Explanation note: Type and paratype specimens collected of Townsendia lemhiensis.