Psilactis tenuis

S. Watson

Proc. Amer. Acad. Arts 26: 139. 1891.

Illustrated
Synonyms: Machaeranthera tenuis (S. Watson) B. L. Turner & D. B. Horne
Treatment appears in FNA Volume 20. Treatment on page 463. Mentioned on page 462.

Annuals or biennials, 25–100 cm. Stems and branches coarsely antrorse or erect-hairy, often scabrous, usually stipitate-glandular distally, sometimes proximally. Distal leaf-blades sessile, linear-lanceolate to narrowly elliptic or linear, smallest 3–4 × 1–1.5 mm. Involucres broadly turbinate, 4–6 mm. Phyllaries linear-lanceolate to linear, equal or slightly unequal, 2.5–5 × 0.3–0.6 mm, bases indurate, margins scarious. Receptacles convex, 1.8–2.5 mm diam. Ray-florets 10–35; laminae 5–8 × 0.7–1 mm. Disc-florets 20–55; corollas 3–4 mm. Ray cypselae 1.2–1.7 mm, sparsely appressed-hairy. Disc cypselae 1.5–2.5 mm, sparsely appressed-hairy; pappi 20–35, 2.5–4 mm. 2n = 8.


Phenology: Flowering (May–)Aug–Oct.
Habitat: Calcareous soils in open oak and pine-oak woodlands, rocky streambeds
Elevation: 1700–2600 m

Distribution

V20-1070-distribution-map.gif

Tex., Mexico (Coahuila), Mexico (Nuevo León), Mexico (Tamaulipas), Mexico (Zacatecas)

Discussion

In the flora area, Psilactis tenuis is known only from the Davis Mountains. Because of its distribution in Mexico, it would be expected to occur in additional areas to the southeast of the Davis Mountains, such as the Glass Mountains and Chisos Mountains. Apparently no records of it exist from those areas.

Selected References

None.

Lower Taxa

None.

"[" is not declared as a valid unit of measurement for this property."]" is not declared as a valid unit of measurement for this property.

... more about "Psilactis tenuis"
not tailed +, rounded +  and obtuse +
distinct +
subequal +
scarious +
usually triangular +  and linear +
usually deltate +  and lanceolate +
indeterminate +  and determinate +
David R. Morgan +
S. Watson +
obovate +  and linear-oblanceolate +
decurrent +
indurate +
compound +  and simple +
rugulose +  and muricate +
stipitate-glandular +  and erect-hairy +
barbellulate +  and barbellate +
not 2-lipped +  and actinomorphic +
yellow +, white +  and blue or purple +
0.3 cm3 mm <br />0.003 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
beaked +, 2-ribbed +  and 5-ribbed +
compressed +, fusiform +  and clavate or obovoid +
fertile +  and bisexual +
white;tawny +
appressed-hairy +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.25 cm2.5 mm <br />0.0025 m <br />) +
persistent +
fertile +  and bisexual +
unequal +
ovate;lanceolate +
linear +  and elliptic +
0.3 cm3 mm <br />0.003 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
linear-lanceolate +
0.1 cm1 mm <br />0.001 m <br /> (0.15 cm1.5 mm <br />0.0015 m <br />) +
Tex. +, Mexico (Coahuila) +, Mexico (Nuevo León) +, Mexico (Tamaulipas) +  and Mexico (Zacatecas) +
1700–2600 m +
appressed-hairy +  and stipitate-glandular +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
Calcareous soils in open oak and pine-oak woodlands, rocky streambeds +
indeterminate +
heterogamous +  and homogamous +
each +  and sessile +
0.4 cm4 mm <br />0.004 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
0.7mm;1mm +
cauline +  and basal +
deltate +  and lanceolate +
lobed +, toothed +  and entire +
2-carpellate +
20 cm200 mm <br />0.2 m <br /> (35 cm350 mm <br />0.35 m <br />) +
Flowering (May–)Aug–Oct. +
0.25 cm2.5 mm <br />0.0025 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
linear-lanceolate +  and linear +
0.03 cm0.3 mm <br />3.0e-4 m <br /> (0.06 cm0.6 mm <br />6.0e-4 m <br />) +
obovate +  and linear-oblanceolate +
Proc. Amer. Acad. Arts +
appressed-hairy +
0.12 cm1.2 mm <br />0.0012 m <br /> (0.17 cm1.7 mm <br />0.0017 m <br />) +
bearing subulate enations +, hairy +  and bristly +
pitted +  and verrucose +
exalbuminous +
Illustrated +
stipitate-glandular +  and erect-hairy +
appendaged +  and truncate +
papillate +  and smooth +
Machaeranthera tenuis +
Psilactis tenuis +
Psilactis +
species +
biennial +  and annual +
25 cm250 mm <br />0.25 m <br /> (100 cm1,000 mm <br />1 m <br />) +
tree +, shrub +  and subshrub +
9 +, 4 +  and 3 +