Lasthenia sect. Amphiachaenia

Annuals or perennials. Leaves entire or ± toothed. Involucres campanulate to depressed-hemispheric, hemispheric, or obconic. Phyllaries ± persistent or falling with cypselae, distinct. Receptacles narrowly conic to conic (subulate in L. leptalea), muricate or papillate, glabrous. Ray corollas bright yellow, laminae 2.5–16 mm, floral pigments turning deep red in dilute aqueous alkali. Disc corolla lobes 5; anther appendages deltate to sublanceolate or subulate (broadened distal to bases); style apices ± deltate with apical tufts of hairs and subapical fringes of shorter hairs. Cypselae to 4 mm; epappose or pappose. 2n = 16, 32, 48.

Distribution

w United States, nw Mexico.

Discussion

Species 4 (4 in the flora).

Perennial lasthenias are found only in sect. Amphiachaenia. Epappose plants of sect. Amphiachaenia are more likely to be found in coastal populations and may constitute entire local populations.

Selected References

Chan, R. 2001. Taxonomic changes and a new species in Lasthenia sect. Amphiachaenia (Compositae: Heliantheae sensu lato). Madroño 48: 205–210.

Chan, R., B. G. Baldwin, and R. Ornduff. 2002. Cryptic goldfields: A molecular phylogenetic reinvestigation of Lasthenia californica sensu lato and close relatives (Compositae: Heliantheae sensu lato). Amer. J. Bot. 89: 1103–1112.

Lower Taxa

Lasthenia californica, Lasthenia gracilis, Lasthenia leptalea, Lasthenia ornduffii

Key

1	Stems glabrous proximally, villous distally; phyllaries usually 4–6, glabrous but for apices; receptacles subulate, papillate; anther appendages subulate; interior w California	Lasthenia leptalea
1	Stems ± hairy throughout, sometimes more so distally; phyllaries 4–16, hairy; receptacles conic, muricate; anther appendages deltate to sublanceolate; Arizona, California, Oregon	> 2
2	Perennials; coastal Oregon	Lasthenia ornduffii
2	Annuals or perennials; coastal or inland Arizona, California, Oregon	> 3
3	Annuals; leaves entire; pappi usually of (2–)4(–6) opaque, white (aging to brown), ovate-lanceolate, aristate scales, sometimes 0; Arizona, California (includingChannel Islands)	Lasthenia gracilis
3	Annuals or perennials (if perennial, only in coastal California); leaves entire or with 3–5+ teeth; pappi 0, or of 1–7 translucent (rarely opaque), brown (rarely white), linear to subulate, aristate scales; n California, s Oregon	Lasthenia californica