Xanthisma texanum

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. 5: 95. 1836.

Common names: Texas sleepy-daisy
IllustratedEndemic
Treatment appears in FNA Volume 20. Treatment on page 385. Mentioned on page 384.

Annuals, rarely biennials; taproots 2–10+ cm. Stems 1–3, usually branched in distal 1/2, sometimes throughout, moderately stout to stout, not wiry, mostly glabrous. Leaves: basal (if persisting) 50–80 × 15–25 mm, pinnatifid, rarely 2-pinnatifid; cauline evenly spaced, proximal often spatulate, distal 2/3 narrowly to broadly lanceolate, 5–35 × 8–12 mm, markedly reduced distally, margins of proximal pinnatifid to coarsely serrate, of distal minutely, evenly serrulate or entire and antrorsely ciliolate, teeth or cilia 50–90+ per side, teeth tipped by white seta 0.1–1.5 mm, faces glabrous. Peduncles moderately to densely hispidulous, eglandular; usually ebracteate. Involucres hemispheric, 5–10 × 11–20 mm. Phyllaries in 3–4 series, faces glabrous; outer usually 1.5–8.5 × 2–5 mm, ciliate; inner 2–10.5 × 1.5–4 mm, often ciliate. Ray-florets 12–34; corollas yellow, tubes 2.5–3 mm, laminae 5–18 × 2–3 mm. Disc-florets 50–200+; corollas 4.5–5 mm. Cypselae 1.6–1.8 mm; pappi 5–6.5 mm, outer lengths often 0.5 longest.

Discussion

Varieties 3 (3 in the flora).

The polymorphic Xanthisma texanum has always been kept distinct from other genera in the tribe, in part due to the unique involucre, here considered a derived structure. The relationship to members of Machaeranthera in the broad sense was never considered until DNA data became available. According to J. C. Semple (1974), the following combination of features characterizes the species: “heterocarpic fruit with a pappus of bristly scales only, fruit pubescence of long white ascending hairs, receptacle slightly convex with a persistent reticulate network of subulate scales.” Interestingly, all of these characters are found in at least some of the taxa of the newly expanded genus.

J. C. Semple (1974) classified varieties texanum and orientale under the typical subspecies (as they are peripherally sympatric and appear to hybridize) and the allopatric X. texanum var. drummondii at the subspecific level. The three taxa are here treated as varieties.

Key

1 Phyllaries abruptly expanded distal to stalks; bodies mostly ovate (3.5–8 × 2.5–5 mm distal to widest point) Xanthisma texanum var. drummondii
1 Phyllaries somewhat expanded distally; bodies mostly orbiculate to depressed-elliptic (1–2 × 1.5–3.5 mm distal to widest point) > 2
2 Phyllary apices rounded, with little or no flare 1 mm from tip Xanthisma texanum var. texanum
2 Phyllary apices obtusely cuspidate, flareddistally, ovate portion 1.5–2 × 2–3 mm (distal to widest point) Xanthisma texanum var. orientale
... more about "Xanthisma texanum"
not tailed +, rounded +  and obtuse +
not bristle-tipped +
not +  and cuspidate +
distinct +
acuminate;obtuse or broadly rounded +
subequal +
scarious +
usually triangular +  and linear +
usually deltate +  and lanceolate +
indeterminate +  and determinate +
Ronald L. Hartman +
de Candolle in A. P. de Candolle and A. L. P. P. de Candolle +
5 cm50 mm <br />0.05 m <br /> (8 cm80 mm <br />0.08 m <br />) +
2-pinnatifid;pinnatifid +
1.5 cm15 mm <br />0.015 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
decurrent +
indurate +
lanceolate;oblanceolate or spatulate +
rugulose +  and muricate +
ovate;orbiculate or depressed +
unequal +
barbellulate +  and barbellate +
0.3 cm3 mm <br />0.003 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
50 (?) +  and 90 (?) +
Texas sleepy-daisy +
not 2-lipped +  and actinomorphic +
0.45 cm4.5 mm <br />0.0045 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
compressed +, narrowly obovoid +  and oblong +
fertile +  and bisexual +
fertile +  and bisexual +
Okla. +  and Tex. +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
discoid +  and radiate +
in corymbiform arrays +  and singly +
indeterminate +
heterogamous +  and homogamous +
each +  and sessile +
0.2 cm2 mm <br />0.002 m <br /> (1.05 cm10.5 mm <br />0.0105 m <br />) +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
0.5 cm5 mm <br />0.005 m <br /> (1 cm10 mm <br />0.01 m <br />) +
hemispheric +
1.1 cm11 mm <br />0.011 m <br /> (2 cm20 mm <br />0.02 m <br />) +
ovate +  and orbiculate or depressed-elliptic +
unequal +
pinnatifid;2-pinnatifid +
sessile +  and short-petiolate +
cauline +  and basal +
not bristle-tipped +
triangular +
entire +  and serrulate +
pinnatifid +  and coarsely serrate +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.85 cm8.5 mm <br />0.0085 m <br />) +
0.2 cm2 mm <br />0.002 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
2-carpellate +
usually whitish +  and brown or reddish-brown +
persistent +
flattened +
0.5 cm5 mm <br />0.005 m <br /> (0.65 cm6.5 mm <br />0.0065 m <br />) +
ebracteate +  and eglandular +
reflexed +, spreading +  and appressed +
linear +  and narrowly oblong or lanceolate +
0.5 cm5 mm <br />0.005 m <br /> (3.5 cm35 mm <br />0.035 m <br />) +
0.8 cm8 mm <br />0.008 m <br /> (1.2 cm12 mm <br />0.012 m <br />) +
0.2 cm2 mm <br />0.002 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. +
bearing subulate enations +, hairy +  and bristly +
flat;convex +
semple1974a +
10 +  and 24 +
exalbuminous +
distinct +
0.01 cm0.1 mm <br />1.0e-4 m <br /> (0.15 cm1.5 mm <br />0.0015 m <br />) +
Illustrated +  and Endemic +
not wiry +  and branched +
sprawling +, spreading +  and erect +
1 +  and 3 +
appendaged +  and truncate +
papillate +  and smooth +
Compositae +
Xanthisma texanum +
Xanthisma sect. Xanthisma +
species +
distinct +
0.02 cm0.2 mm <br />2.0e-4 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
0.25 cm2.5 mm <br />0.0025 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
biennial +  and annual +
20 cm200 mm <br />0.2 m <br /> (70 cm700 mm <br />0.7 m <br />) +