Stephanomeria pauciflora |
Stephanomeria elata |
|
---|---|---|
brownplume wirelettuce, few-flower wirelettuce, prairie skeletonplant, wire-lettuce |
Nuttall's wirelettuce, Santa Barbara stephanomeria, Santa Barbara wirelettuce |
|
Habit | Perennials, 20–50 cm (caudices woody). | Annuals, 50–150 cm. |
Stems | 1–5+, divaricately and intricately branched (often forming dense bushes), usually glabrous, rarely tomentose. |
single, branches ascending or spreading, glabrous, puberulent, or glandular-pubescent. |
Leaves | withered at flowering; basal blades linear-lanceolate, runcinate, 3–7 cm, margins pinnately lobed (faces glabrous); cauline much reduced and bractlike. |
withered at flowering (glabrous or puberulent); basal blades linear to oblanceolate, runcinate, 3–10 cm, margins pinnately lobed; cauline much reduced, bractlike. |
Peduncles | 3–10 mm. |
3–7 mm. |
Involucres | 8–11 mm (phyllaries 4–6, glabrous). |
5–7 mm (glabrous, puberulent, or stipitate-glandular). |
Florets | 5–6. |
9–15. |
Calyculi | of appressed bractlets. |
of usually reflexed, rarely appressed bractlets. |
Heads | borne singly along branches. |
borne singly or clustered along branches. |
Cypselae | tan, 3.5–5 mm, faces tuberculate, grooved; pappi of 15–20, usually tan, rarely white, bristles (connate in groups of 2–4, bases persistent), plumose on distal 80%. |
light tan to dark brown, 2.8–4.5 mm, faces smooth to strongly tuberculate, grooved; pappi of 17–22 white or tan bristles (falling or widened bases persistent, bases connate in groups of 2–4, distal portions breaking off), wholly plumose. |
2n | = 16. |
= 32. |
Stephanomeria pauciflora |
Stephanomeria elata |
|
Phenology | Flowering May–Sep. | Flowering Jul–Oct. |
Habitat | Sandy, gravelly washes and slopes in desert shrub communities, juniper woodlands, open, sandy short-grass plains | Chaparral openings, grassy meadows, forest openings, roadsides, often growing as weed |
Elevation | 200–1500 m (700–4900 ft) | 100–1400 m (300–4600 ft) |
Distribution |
AZ; CA; CO; KS; NM; NV; OK; TX; UT; WY; Mexico (Chihuahua, Sonora)
|
CA; OR
|
Discussion | Stephanomeria pauciflora generally grows as an intricately branched, often rounded bush. Occasional plants, usually from Arizona, New Mexico, Texas, and southern Utah, have long, flexuous stems and branches, an architecture that resembles one of the typical forms of S. tenuifolia. Some plants of S. pauciflora have white pappi, also typical of S. tenuifolia. It is not known if these plants represent uncommon and unusual individuals or if they are from populations in which all plants have those traits. It is also not known whether such plants of S. pauciflora grow near populations of S. tenuifolia; if so, they may result from interspecific hybridization. That is a possibility; experimental hybrid plants produced by crossing individuals from the two species were about 20% fertile. Such fertility suggests the species are sufficiently compatible that fully fertile segregants with variously intermediate morphologies could be expected where they hybridize in nature. The experimental crosses were made reciprocally between S. pauciflora from Riverside County, California (L. D. Gottlieb 6653), and S. tenuifolia from Wheeler County, Oregon (L. D. Gottlieb 6692); specimens of the six F1 hybrid plants that were produced are deposited at DAV. Plants of S. pauciflora that are densely tomentose throughout are occasionally found, particularly in the deserts of California and Nevada, and have been named S. cinerea or S. pauciflora var. parishii. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Stephanomeria elata grows in the coastal foothills and mountains, the western slopes of Sierra Nevada, and southwest Oregon. All the tetraploid populations of annual stephanomerias are placed into Stephanomeria elata. The plants are self-compatible and are highly self-pollinating. Stephanomeria elata is an allotetraploid species that arose following hybridization between S. exigua and S. virgata (L. D. Gottlieb 1972). Substantial interpopulation morphologic variability occurs in the length, width, and color of ligules, number of florets, and degree of reflexing of bractlets of the calyculi. Two groups of populations can be distinguished. One group has large cypselae, averaging 3.9–4.5 mm, the bristle bases are widened, and about 30% of the pollen grains have four pores. The second group has smaller cypselae, averaging 2.8–3.3 mm, the bristle bases are not widened, and less than 10% of the pollen grains have four pores. The former group of populations is generally found from southwestern Oregon south to Monterey County in the Coast Ranges of California and on the western slopes of the Sierra Nevada to Fresno County. The latter group is distributed near the coast from Marin County to Santa Barbara County, California. The two groups overlap in Santa Cruz, Santa Clara, and Monterey counties; the distinctions are less evident there. Stephanomeria elata and its parents S. exigua and S. virgata form a polyploid complex that perplexed taxonomists for many years. Once the morphologic distinctions between parental species were clarified (L. D. Gottlieb 1972), particularly, the presence versus absence of the longitudinal groove on each face of their cypselae that distinguishes S. exigua and S. elata from S. virgata, and the allotetraploidy of S. elata was recognized, it has become much simpler to distinguish the three species in the field. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 19, p. 356. | FNA vol. 19, p. 353. |
Parent taxa | Asteraceae > tribe Cichorieae > Stephanomeria | Asteraceae > tribe Cichorieae > Stephanomeria |
Sibling taxa | ||
Synonyms | Prenanthes pauciflora, S. cinerea, S. lygodesmoides, S. pauciflora var. parishii | |
Name authority | (Torrey) A. Nelson: in J. M. Coulter and A. Nelson, New Man. Bot. Centr. Rocky Mt., 588. (1909) | Nuttall: Proc. Acad. Nat. Sci. Philadelphia 4: 20. (1848) |
Web links |