Layia

Hooker & Arnott ex de Candolle in A. P. de Candolle and A. L. P. P. de Candolle

in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 7: 294. 1838.

Etymology: For George Tradescant Lay, a naturalist on Beechey’s voyage (1825–1828)
Treatment appears in FNA Volume 21. Treatment on page 262. Mentioned on page 255, 259, 260, 263, 264.
 TaxonIllustrator 
FNA21 P42 Lagophylla ramosissim.jpegLagophylla ramosissima
Layia platyglossa
Layia glandulosa
Barbara Alongi
Yevonn Wilson-Ramsey
Yevonn Wilson-Ramsey

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, or bicolored. Disc-florets 5–120+, bisexual, fertile; corollas yellow, tubes shorter than funnelform throats, 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.

Distribution

w North America, nw Mexico

Discussion

Species 14 (14 in the flora).

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.

Selected References

None.

Key

1 Disc pappi 0 > 2
1 Disc pappi of 1–32 bristles or scales > 7
2 Plants not glandular; paleae subtending ± all disc florets Layia chrysanthemoides
2 Plants glandular; paleae in 1 (involucre-like) series between ray and disc florets > 3
3 Plants apple- or banana-scented; margins (basal leaves) usually denticulate to serrulate, seldom lobed; ray corollas white to cream Layia heterotricha
3 Plants unscented, or not apple- or banana-scented; margins (basal leaves) lobed; ray corollas white, yellow, or bicolored (proximally yellow, distally whitish) > 4
4 Stems usually purple-streaked; involucres campanulate to hemispheric, subglobose, or ± urceolate > 5
4 Stems usually not purple-streaked; involucres ± hemispheric > 6
5 Involucres campanulate to hemispheric or subglobose; ray florets 6–18, corollas yellow or bicolored (proximally yellow, distally whitish) Layia gaillardioides
5 Involucres ± urceolate; ray florets 13–27 (in 2 series), corollas bicolored Layia jonesii
6 Plants strongly lemon- or acrid-scented; ray corollas white or yellow; anthersyellow or brownish Layia pentachaeta
6 Plants not strongly scented; ray corollas yellow or bicolored (proximally yellow, distally white); anthers ± dark purple (sometimes yellow to brownish in sw California) Layia platyglossa
7 Ray florets 0 Layia discoidea
7 Ray florets 3–27 (ray laminae sometimes inconspicuous) > 8
8 Plants not glandular; paleae subtending ± all disc florets > 9
8 Plants glandular; paleae in 1 (involucre-like) series between ray and disc florets > 10
9 Disc pappi of unequal, subulate to setiform scales Layia chrysanthemoides
9 Disc pappi of ± equal, lance-attenuate scales Layia fremontii
10 Disc pappi of elliptic, lance-linear, or ovate, non-plumose, non-woolly scales (bases sparsely setose), 0.5–3.5 mm > 11
10 Disc pappi usually of bristles or setiform scales, if scales linear-attenuate to subulate, then proximally plumose and often proximally woolly adaxially, 1–7 mm > 13
11 Ray corollas white; anthers yellow to brownish; ray cypselae sparsely hairy Layia leucopappa
11 Ray corollas yellow or bicolored (proximally yellow, distally white); anthers ± dark purple; ray cypselae glabrous or sparsely hairy > 12
12 Stems usually purple-streaked; involucres ± urceolate; ray florets 13–27 (in 2 series); ray cypselae glabrous; pappus scales 0.5–2 mm Layia jonesii
12 Stems not purple-streaked; involucres hemispheric to ± urceolate; ray florets 6–15; ray cypselae glabrous or sparsely hairy; pappusscales 2–3.5 mm Layia munzii
13 Plants usually not strongly scented (if not contacted); disc pappus bristles or scales mostly proximally plumose and adaxially woolly, sometimes ± scabrous throughout, if proximally plumose and not woolly, then linear-attenuate to subulate scales > 14
13 Plants usually strongly scented, even without contact (except L. carnosa, fleshy-leaved plants of coastal dunes); disc pappus bristles or scales proximally plumose, seldom woolly adaxially (not linear-attenuate to subulate) > 16
14 Ray corollas usually white (sometimes yellow); disc pappi of 10–15 linearattenuate to subulate scales Layia glandulosa
14 Ray corollas yellow or bicolored (proximally yellow, distally white); disc pappi of 14–32 bristles or setiform scales > 15
15 Involucres usually ± hemispheric; phyllary apices often longer than folded bases; ray corollas yellow or bicolored (proximally yellow, distally white); anthers usually ± dark purple (sometimes yellow to brownish in sw California); disc pappus bristles or scales usually scabrous (sometimes proximally plumose and adaxially woolly in sw California) Layia platyglossa
15 Involucres ± ellipsoid to campanulate; phyllary apices usually shorter than folded bases; ray corollas yellow; anthers yellow to brownish; disc pappus bristles orscales proximally plumose and adaxially woolly Layia septentrionalis
16 Margins (basal leaves) usually denticulate or serrulate, seldom toothed or lobed;ray corollas white to cream (disc pappi readily falling as units) Layia heterotricha
16 Margins (basal leaves) lobed; ray corollas white, yellow, or bicolored (proximally yellow, distally whitish) > 17
17 Anthers yellow to brownish Layia pentachaeta
17 Anthers ± dark purple > 18
18 Stems not purple-streaked; ray corollas white, laminae 1.5–3.5 mm; ray cypselae sparsely hairy Layia carnosa
18 Stems purple-streaked; ray corollas yellow or bicolored (proximally yellow, distally white), laminae 1–18 mm; ray cypselae glabrous > 19
19 Ray corollas yellow or bicolored (proximally yellow, distally whitish), 3.5–18 mm; disc pappi of 15–24 bristles or setiform scales (main stemsascending, not strictly erect) Layia gaillardioides
19 Ray corollas yellow, 1–4 mm; disc pappi of 10–16 bristles or setiform scales (main stems strictly erect) Layia hieracioides
... more about "Layia"
not tailed +, rounded +  and obtuse +
pale +  and dark +
connate +  and distinct +
subequal +
scarious +
usually ovate +  and lanceolate +
usually deltate +  and lanceolate +
umbelliform +, spiciform +, paniculiform +, glomerulate +  and corymbiform +
indeterminate +  and determinate +
Bruce G. Baldwin +, Susan J. Bainbridge +  and John L. Strother +
Hooker & Arnott ex de Candolle in A. P. de Candolle and A. L. P. P. de Candolle +
decurrent +
compound +  and simple +
linear to linear-elliptic +
1-2-pinnatifid;oblanceolate;linear +
winged;ribbed;winged;ribbed +
tuberculate +  and rugose +
barbellulate +  and barbellate +
yellow +, bicolored +, white +  and cream +
hairy +  and glabrous +
fusiform +, clavate +, obpyramidal +, terete +, compressed +  and obcompressed +
fertile +  and bisexual +
fertile +  and bisexual +
w North America +  and nw Mexico +
For George Tradescant Lay, a naturalist on Beechey’s voyage (1825–1828) +
hirsute +  and strigose +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
in more or less corymbiform arrays +  and singly +
indeterminate +
homogamous +  and heterogamous +
each +  and sessile +
0.2 cm2 mm <br />0.002 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
urceolate;obconic;urceolate;obconic;ellipsoid;cylindric;campanulate;hemispheric +
petiolate +  and sessile +
alternate +  and opposite +
deltate +
dentate to pinnatifid or palmatifid +  and entire +
2-carpellate +
persistent +
of 1 +  and 32 elliptic +
subulate +, setiform +, ovate +  and lance-attenuate +
3 +  and 27 +
alternate +  and opposite +
in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. +
clavate +  and obcompressed +
flat;convex +
plumose +
exalbuminous +
appendaged +  and truncate +
hirsutulous +  and glabrous +
papillate +
Compositae +
Asteraceae (tribe Heliantheae) subtribe Madiinae +
cylindric +
entire +  and toothed +
60 cm600 mm <br />0.6 m <br /> (130 cm1,300 mm <br />1.3 m <br />) +
2 cm20 mm <br />0.02 m <br /> (60 cm600 mm <br />0.6 m <br />) +
shrub +  and subshrub +