Streptanthus squamiformis

Goodman

Rhodora 58: 354. 1957.

EndemicConservation concern
Treatment appears in FNA Volume 7. Treatment on page 721. Mentioned on page 703.

Annuals; sparsely to densely pubescent or glabrous. Stems (simple from base), unbranched or branched distally, 1.5–8.5 (–11) dm, (sparsely to densely hirsute basally, usually glabrous distally, rarely throughout). Basal leaves (withered by flowering); not rosulate; petiolate; blade similar to cauline. Cauline leaves: blade ovate to oblong or lanceolate, 1–9 cm × 5–30 mm, (smaller distally), base amplexicaul, margins usually entire, rarely shallowly dentate, (midvein abaxially glabrous or pubescent, surfaces glabrous distally). Racemes ebracteate, (dense to lax). Fruiting pedicels divaricate-ascending, (straight), 5–16 mm, (glabrous or pubescent). Flowers: calyx campanulate; sepals purplish, 4–7 mm, not keeled, (hirsute, trichomes 0.7–2 mm, both pairs with subapical callosities, 1–2.5 mm); petals purple (with dark purple center), 9–17 (–20) mm, blade 5–10 × 5–7 mm, margins not crisped, claw 4–7 mm, narrower than blade; stamens tetradynamous; filaments: median pairs (distinct), 5–6 mm, lateral pair 3–4 mm; anthers (all) fertile, 1.5–2.8 mm; gynophore 1–1.5 mm. Fruits ascending to suberect, smooth, straight, flattened, 0.6–1.4 cm × 2–3 mm; valves each with prominent midvein; replum straight; ovules 54–86 per ovary; style 1–1.5 mm; stigma strongly 2-lobed. Seeds broadly oblong, 2–2.7 × 1–1.2 mm; wing 0.1–0.25 mm wide, continuous.


Phenology: Flowering Apr–May.
Habitat: Glades, steep slopes, sandstone and soft shale in ravines or rocky openings in oak-pine-hickory forests

Discussion

Of conservation concern.

Streptanthus squamiformis is known from the Ouachita Mountains in Arkansas (Howard, Polk, and Sevier counties) and Oklahoma (McCurtain County).

The similarities between Streptanthus squamiformis and S. maculatus in most aspects are truly remarkable, especially in foliage, fruits, seeds, and flower color and size. The former differs by having the sepals densely pubescent (versus glabrous) with trichomes to 2 mm, both sepal pairs with subapical callosities 1–2 mm (versus callosities absent or, rarely, present on lateral sepals and 0.1–0.3 mm), smaller anthers (1.5–2.7 versus 3–4 mm), and pubescent or, sometimes, glabrous (versus always glabrous) fruiting pedicels.

Selected References

None.

Lower Taxa

None.

"narrower" is not a number."elongated" is not a number."thick" is not a number."dm" is not declared as a valid unit of measurement for this property.

... more about "Streptanthus squamiformis"
linear +  and oblong +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.28 cm2.8 mm <br />0.0028 m <br />) +
Ihsan A. Al-Shehbaz +
Goodman +
appendaged +  and unappendaged +
0.5 cm5 mm <br />0.005 m <br /> (1 cm10 mm <br />0.01 m <br />) +
lyrate-pinnatifid +, dentate +  and entire +
dissected +, repand +, sinuate +, crenate +  and dentate +
ovate;oblong or lanceolate +
much smaller +  and reduced +
5mm;7mm +
campanulate +
branched +  and simple +
petiolate +  and sessile +
well-developed +
distinct +
0.4 cm4 mm <br />0.004 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
differentiated +
emarginate +  and entire +
Ark. +  and Okla. +
straight +  and curved +
not winged +  and unappendaged +
connate +  and distinct +
lateral +  and median +
0.3 cm3 mm <br />0.003 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
zygomorphic +  and actinomorphic +
latiseptate +, stipitate +  and subsessile +
straight +
0.6cm;1.4cm +
ascending +  and suberect +
flattened +
0.2 cm2 mm <br />0.002 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
0.1 cm1 mm <br />0.001 m <br /> (0.15 cm1.5 mm <br />0.0015 m <br />) +
Glades, steep slopes, sandstone and soft shale in ravines or rocky openings in oak-pine-hickory forests +
sessile +  and petiolate +
alternate +, not +  and rosulate +
cauline +  and basal +
connate +  and distinct +
decurrent +
dentate +  and entire +
not crisped +
tenuinucellate +, crassinucellate +  and bitegmic +
campylotropous +  and anatropous +
unequal +
1.7 cm17 mm <br />0.017 m <br /> (2 cm20 mm <br />0.02 m <br />) +
Brownish (?) +, Purple (?) +, Pink (?) +, Yellow (?) +  and White (?) +
rudimentary +
Oblong (?) +  and Ovate (?) +
0.9 cm9 mm <br />0.009 m <br /> (1.7 cm17 mm <br />0.017 m <br />) +
Flowering Apr–May. +
trinucleate +  and 3(-11)-colpate +
elongated +
divaricate-ascending +
stout +  and slender +
0.5 cm5 mm <br />0.005 m <br /> (1.6 cm16 mm <br />0.016 m <br />) +
mucilaginous +
aseriate +, uniseriate +  and biseriate +
not +  and mucilaginous +
White (?) +, Black (?) +, Brown (?) +  and Yellow (?) +
0.2 cm2 mm <br />0.002 m <br /> (0.27 cm2.7 mm <br />0.0027 m <br />) +
0.1 cm1 mm <br />0.001 m <br /> (0.12 cm1.2 mm <br />0.0012 m <br />) +
persistent +  and caducous +
distinct +
not keeled +
0.4 cm4 mm <br />0.004 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
reduced +
latiseptate +, schizocarpic +, samaroid +  and lomentaceous +
indehiscent +  and dehiscent +
angustiseptate +, flat +, angled +, terete +, torulose +, not +, segmented +  and nutletlike +
Endemic +  and Conservation concern +
tetradynamous +
branched +  and unbranched +
procumbent +  and decumbent +
ascending +  and erect +
subsessile +, sessile +  and petiolate +
persistent +
distinct +
0.1 cm1 mm <br />0.001 m <br /> (0.15 cm1.5 mm <br />0.0015 m <br />) +
Agianthus +, Cartiera +, Disaccanthus +, Euklisia +, Icianthus +, Mesoreanthus +, Microsemia +, Mitophyllum +  and Pleiocardia +
Streptanthus squamiformis +
Streptanthus +
species +
dendritic +  and simple +
coiled +, 1-7-veined +  and veined +
pubescent +  and glabrous +
anastomosing +
glabrous +  and pubescent +
perennial +, biennial +  and annual +
subshrub +  and shrub +
aquatics +  and terrestrial +
glabrous +  and pubescent +
0.1mm;0.25mm +