Jepson Flora Project: Jepson Interchange    

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Jepson Interchange (more information)
©Copyright 1993 by the Regents of the University of California

  • Up-to-date information about California vascular plants is available from the Jepson eFlora.



David J. Keil, Family Editor and author, except as specified

Annual to tree
Leaves basal or cauline, alternate to whorled, simple to compound
Inflorescence: 1° inflorescence a head, each resembling a flower, 1–many, generally arrayed in cymes, generally subtended by ± calyx-like involucre; flowers 1–many per head
Flowers bisexual, unisexual, or sterile, ± small, of several types; calyx 0 or modified into pappus of bristles, scales, or awns, which is generally persistent in fruit; corolla radial or bilateral (rarely 0), lobes generally (0)4–5; stamens 4–5, anthers generally fused into cylinder around style, often appendaged at tips, bases, or both, filaments generally free, generally attached to corolla near throat; pistil 1, ovary inferior, 1-chambered, 1-seeded, style 1, branches 2, generally hair-tufted at tip, stigmas 2, generally on inside of style branches
Fruit: achene, cylindric to ovoid, generally deciduous with pappus attached
Genera in family: ± 1300 genera, 21,000 species (largest family of dicots): worldwide. Largest family in CA. Also see tribal key to CA genera: Strother 1997 Madroño 44(1):1–28. See glossary p. 25 for illustrations of general family characteristics.



Perennial, subshrubs, shrubs
Stems generally white, glabrous or hairy
Leaves simple, alternate, entire or toothed; midrib white
Inflorescence: heads radiate, solitary, peduncled; involucre bell-shaped or hemispheric; phyllaries graduated in several series; receptacle convex, naked
Ray flowers generally many; corollas white to blue or purple
Disk flowers many; corolla yellow; style tips linear, acute
Fruit linear to club-shaped, weakly compressed, covered with long, appressed hairs; pappus of many, unequal bristles
Species in genus: 8 spp: w North America:
Etymology: (Greek: woody root)
Reference: [Watson 1977 Brittonia 29:199–216]


X. orcuttii (Vasey & Rose) Greene


Shrub < 1.5 m
Stems glabrous (rarely puberulent below heads)
Leaves 2–6 cm, oblanceolate to oblong or lanceolate, glabrous or sparsely hairy on margins, obtuse or acute, ± spiny-dentate or entire, not much reduced upward
Inflorescence: heads sessile (or peduncle < or = 11 cm); phyllaries 5–12 mm, 1.5–3.5 mm wide, glabrous, innermost = or > immediately preceding series
Ray flowers 25–40; tube 4–6 mm; ligule 1.2–3.2 cm, light blue
Disk flowers 55–140; corolla 8–10.5 mm
Fruit 3–4 mm; pappus bristles < or = 12 mm
Chromosomes: 2n=12
Ecology: Arid canyons
Elevation: 20–300 m.
Bioregional distribution: s Sonoran Desert (Imperial, San Diego cos.)
Flowering time: Mar–Apr
Synonyms: Machaeranthera o. (Vasey & Rose) Cronquist & D.D. Keck
See the CNPS Inventory for information about endangerment and rarity.
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