Chrysothamnus molestus |
Chrysothamnus stylosus |
|
---|---|---|
Arizona rabbitbrush |
pillar false gumweed, resinbush |
|
Habit | Shrubs, 8–20 cm; with woody, highly branched caudices, bark dark gray, highly fibrous with age. | Shrubs, 40–120 cm; with woody, freely branched caudices (not readily differentiated from young shoots). |
Stems | ascending, green, ± puberulent, stipitate-glandular. |
green when young, soon becoming tan to white or grayish with age (bark of older stems flaky), branched, resinous when young, less so with age. |
Leaves | erect to closely ascending; sessile; blades with ± evident midnerves, linear to narrowly elliptic, 7–20 × 0.7–1.5 mm, sulcate, sometimes apiculate, apices acute, faces moderately puberulent, uniformly stipitate-glandular. |
ascending to spreading, becoming deflexed; sessile; blades with conspicuous midnerves plus 1–2 pairs of collaterals often evident, lanceolate to linear-elliptic, falcate, 6–35(–60) × 1–9 mm, often folded, margins sometimes undulate, apices acute, mucronate, ± spinulose, faces glabrous, ± gland-dotted, resinous. |
Involucres | subcylindric, 9–11 × 2.5–3.5 mm. |
hemispheric, 8–12 × 9–15 mm. |
Disc florets | 5; corollas 5.5–7.5 mm, lobes 0.9–1.5 mm; style branches 2.7–3.2 mm, appendages 1–1.7 mm. |
30–40+; corollas 6–8.5 mm, lobes 1–1.7 mm; style branches 2.8–3.5, appendages 1.3–1.7 mm. |
Phyllaries | ± 20 in 4–5 series, in 4–5 strong vertical ranks, tan, often with green or dark subapical splotch, midnerves often obscure, linear or lanceolate to elliptic, 2–9 × 0.5–1.3 mm, unequal, outer ± herbaceous, inner chartaceous, strongly keeled, apices acute to rounded, tip cupped, faces of outer glabrous or puberulent. |
40–60+ in 3–5 series, in spirals, mostly tan, ovate to lanceolate, unequal, 3–10 × 1–1.8 mm, greenish distally but scarcely herbaceous, apices acute or acuminate, often recurved, faces often glutinous. |
Heads | in small cymiform to racemiform arrays. |
usually in dense, cymiform arrays (to 7 cm wide), rarely borne singly, not overtopped by distal leaves. |
Cypselae | tan, elliptic, 4.2–6 mm, mostly 5-ribbed, faces glabrous, sparsely glandular; pappi tan, 6–7.5 mm. |
tan, narrowly cylindric, 4–5 mm, glabrous or sparsely hairy, resinous; pappi of 12–15, white or stramineous, lanceolate to lance-linear scales 2–4 mm. |
2n | = 18. |
= 18. |
Chrysothamnus molestus |
Chrysothamnus stylosus |
|
Phenology | Flowering late summer–fall. | Flowering summer–fall. |
Habitat | Rocky soils, mostly on limestone pinyon-juniper woodland | Canyonlands, dunes, in sandy soils, with 4-winged saltbush, ephedra, sand dropseed, blackbrush, and juniper |
Elevation | 1800–2400 m (5900–7900 ft) | 1100–1700 m (3600–5600 ft) |
Distribution |
AZ |
AZ; UT
|
Discussion | Chrysothamnus molestus is known only from Coconino County. It is in the Center for Plant Conservation’s National Collection of Endangered Plants. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Chrysothamnus stylosus has been treated previously in the monotypic genus Vanclevea. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 20, p. 190. | FNA vol. 20, p. 190. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | C. viscidiflorus var. molestus | Grindelia stylosa, Vanclevea stylosa |
Name authority | (S. F. Blake) L. C. Anderson: Madroño 17: 222. (1964) | (Eastwood) Urbatsch: Sida 21: 1627. (2005) |
Web links |