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hispid false mallow

Habit Herbs, annual, (0.05–)0.1–0.5(–0.8) m, bushy-branched.
Stems

erect, sparsely or moderately hairy, hairs appressed, 4(–6)-rayed, normally bilateral and swollen-based.

Leaves

stipules persistent, linear, 3–5 × 0.3 mm, apex acuminate;

petiole 5–10 mm;

blade lanceolate to linear-lanceolate, unlobed, 2.5–3.5 × 0.5–1 cm, not much reduced distally, at least 3 times longer than wide, 3–4 times longer than petiole, base rounded to cuneate, margins sparsely serrate-dentate, apex acute, surfaces stellate-hairy, hairs scattered, appressed, (2–)4–6(–8)-rayed, reduced to simple hairs at margins.

Inflorescences

axillary solitary flowers in distal 1/2 of plant;

floral bracts absent.

Pedicels

2–4(–10) mm, to 5–8(–17) mm in fruit;

involucellar bractlets free from or basally adnate to calyx for 0.5–1 mm, narrowly lanceolate to linear, subfalcate, 3–7 × 0.3–0.6 mm, 1/2 times length of calyx lobes, apex acuminate.

Flowers

calyx connate 2/5–1/2 its length, broadly campanulate, distinctly plicate-angular due to prolonged reniform-auriculate lobe bases, 5–7 mm, accrescent to 8–10 mm, somewhat inflated in fruit, surface hairy, hairs both 4–6-rayed, stellate and simple to 2-rayed marginal;

corolla wide-spreading, yellow to pale yellow-orange, 5 mm diam., petals asymmetrically obovate, shallowly lobed, 3–4.5 × 2–3.5 mm, subequal to or exceeding calyx by 0.5–1 mm;

staminal column 1–1.6 mm, glabrous;

style 5- or 6-branched.

Seeds

2–2.5 mm.

Schizocarps

6–8 mm diam.;

mericarps readily shed from calyx, 5 or 6, 2.6–3.5 × 2.6–3.5 × 1.5 mm, dehiscent, separating into 2 valves, short-notched, mucro absent, hairy, hairs both minute, simple and longer erect, simple, to 1 mm on proximal-apical surface, sides rounded, smooth and unribbed.

2n

= 36.

Malvastrum hispidum

Phenology Flowering summer; frost-sensitive.
Habitat Open limestone and dolomite outcrops, cedar glades, prairies, shallow soil
Elevation 50–300 m (200–1000 ft)
Distribution
from FNA
AL; AR; IA; IL; KS; KY; MO; OK; TN; VA
[WildflowerSearch map]
Discussion

Malvastrum hispidum is local in distribution. The seeds are very thick-walled and persist in the seed bank for many years, but the plants survive only in areas with little other vegetation and will disappear when there is much competition from other species. It appears to benefit from occasional fires. While it is clearly related to the other species of the genus, its dehiscent mericarps, narrow leaves, distribution, and strictly annual duration easily distinguish it. Open flowers are only infrequently seen; most appear to be cleistogamous. Its origins and exact relationships are somewhat obscure.

Collections of the species from Iowa are historic; no recent ones are known from there. It is endangered in Illinois and Virginia. There are very few recent collections from Kentucky. Its status in Arkansas, Kansas, and Oklahoma is uncertain. In Alabama it is quite rare and occurs only in a few cedar glades near the Tennessee border. The species appears to be most secure in Missouri and Tennessee.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 6, p. 297.
Parent taxa Malvaceae > subfam. Malvoideae > Malvastrum
Sibling taxa
M. americanum, M. aurantiacum, M. bicuspidatum, M. corchorifolium, M. coromandelianum
Synonyms Sida hispida, M. angustum, Sidopsis hispida, Sphaeralcea angusta
Name authority (Pursh) Hochreutiner: Annuaire Conserv. Jard. Bot. Genève 20: 129. (1917)
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