Overview
Annuals, 2-60(-130) cm. Stems usually ± erect (prostrate in L. chrysanthemoides and L. platyglossa of coastal bluffs). Leaves mostly cauline; proximal opposite, most alternate; sessile; blades ovate, lanceolate, or oblanceolate to linear, sometimes 1-2-pinnatifid, ultimate margins toothed or entire, faces glabrous or hirsute to strigose (distal leaves sometimes stipitate-glandular as well). Heads usually radiate (discoid in L. discoidea), borne singly or in ± corymbiform arrays. Peduncular bracts: pit-glands, tack-glands, and/or spines 0. Involucres ± hemispheric, campanulate, cylindric, ellipsoid, obconic, or urceolate, 2-15+ mm diam. Phyllaries 0 (then outer paleae functioning as phyllaries, in L. discoidea), or 3-27 in 1(-2) series (lanceolate to lance-attenuate or oblanceolate, herbaceous, each usually wholly enveloping a subtended ray ovary, abaxially hirsute to strigose or scabrous, sometimes glandular). Receptacles flat to convex, setulose, paleate (paleae falling, in 1 series, between rays and discs or subtending ± all disc florets, distinct, phyllary-like, more scarious). Ray florets 0 or 3-27, pistillate, fertile; corollas yellow, cream, white< /span>, or bicolored. Disc florets 5-120+, bisexual, fertile; corollas yellow, tubes shorter than funnelform throats< /span>, lobes 5, deltate (anthers ± dark purple or yellow to brownish; styles glabrous proximal to branches). Ray cypselae obcompressed, clavate (± arcuate to falcate, basal attachments central, apices beakless, faces glabrous or sparsely hairy) ; pappi 0. Disc cypselae ± clavate (usually ± strigose to sericeous, sometimes glabrous) ; pappi 0 or of 1-32 elliptic, lance-attenuate, ovate, setiform, or subulate, glabrous, scabrous, or plumose scales or bristles (often each basally villous and/or adaxially woolly). x = 8.
Species 14: w North America, nw Mexico.
Layia is evidently most closely related to Lagophylla based on molecular phylogenetic data. Species of Layia with 2n = 14 constitute a clade that has been regarded as exemplary of geographic diversification (speciation) in plants (J. Clausen 1951; B. G. Baldwin, unpubl.). All members of Layia except L. carnosa and L. hieracioides are self-incompatible.[1]
Taxonomy
The Genus Layia is further organized into finer groupings including:
- Species: ZipcodeZoo has pages for 33 species, subspecies, varieties, forms, and cultivars in the Genus Layia: L. · L. calliglossa · L. carnosa (Beach Tidytips) · L. chrysanthemoides (Smooth Tidy-Tips) · L. chrysanthemoides chrysanthemoides (Smooth Tidytips) · L. congdonii · L. discoidea (Rayless Tidytips) · L. douglasii · L. elegans · L. emarginata · L. fremontii (Fremont's Tidy-Tips) · L. gaillardioides (Woodland Tidy-Tips) · L. glandulosa (Whitedaisy Tidytips) · L. glandulosa subsp. lutea (Whitedaisy Tidytips) · L. glandulosa typica · L. glandulosa var. hispida · L. heterotricha (Pale-Yellow Tidy-Tips) · L. hieracioides (Tall Tidy-Tips) · L. hispida · L. jonesii (Jones' Tidytips) · L. leucopappa (Comanche Point Tidytips) · L. munzii (Munz's Tidy-Tips) · L. nemorosa · L. paniculata · L. pentachaeta (Sierran Tidy-Tips) · L. pentachaeta albida (Sierra Tidytips) · L. pentachaeta var. albida · L. pentachaeta var. hanseni · L. platyglossa (Yellow-Daisy Tidy-Tips) · L. platyglossa 'Tidy Tips' · L. platyglossa campestris (Coastal Tidytips) · L. septentrionalis (Colusa Tidy-Tips) · L. ziegleri
Footnotes
- Bruce G. Baldwin, Susan J. Bainbridge, John L. Strother "Layia". in Flora of North America Vol. 21 Page 255, 259, 260, 262, 263, 264. Oxford University Press. Online at EFloras.org.
Sources
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