Malvastrum coromandelianum
Malvastrum
common false mallow, three-lobed false mallow, threelobe false mallow
false mallow
erect or decumbent, hairs scattered, appressed, bilateral, (2–)4-rayed, swollen-based, not sublepidote, hairs 1–3 mm.
erect or ascending to decumbent.
stipules persistent, lanceolate, subfalcate to falcate, 3–6 × 0.5–1 mm, apex acuminate;
petiole 10–20(–40) mm;
blade ovate to ± lanceolate, unlobed, (1.7–)3–4(–6.5) × (0.6–)1.5–3(–5.5) cm, 1.1–2.8 times longer than wide, 2.5–4.5 times longer than petiole, not greatly reduced on stem distally, base truncate to broadly-rounded to often wide-cuneate, margins dentate to serrate, apex acute, surfaces sparsely hairy, hairs bilateral, 2–4-rayed, stellate or with simple hairs on adaxial surface.
stipules persistent [deciduous], lanceolate to linear [wide-ovate], usually subfalcate or falcate;
blade wide-ovate to lanceolate, unlobed or sometimes obscurely 3-lobed, base rounded, slightly cordate, nearly truncate, to cuneate, margins crenate-dentate to dentate-serrate or denticulate.
axillary, solitary flowers, flowers sometimes congested towards branch tips;
floral bracts absent.
axillary solitary flowers, terminal racemes or spikes in distal 1/2 of plant;
involucel present, bractlets persistent, 3, distinct, free or adnate basally to calyx.
1–2 mm, to 3–5 mm in fruit;
involucellar bractlets basally adnate to calyx for 0.5–1 mm, lanceolate, subfalcate, 4–6 × 0.6–1 mm, shorter than calyx lobes, apex acute.
calyx not inflated (slightly so in M. hispidum), somewhat accrescent, lobes 3–5-ribbed, deltate to narrowly triangular;
corolla campanulate to wide-spreading, yellow to yellow-orange;
staminal column included;
ovary (5–)8–18-carpellate;
ovules 1 per cell;
style 5–18-branched (equal in number to locules);
stigmas capitate.
schizocarps, erect, not inflated, oblate-discoid, usually depressed in center, somewhat indurate at maturity;
mericarps (5–)8–18, drying tan or brown, without dorsal spurs or with 1–3 apical (dorsal) spurs (mucros or cusps) 0.1–2.3 mm, sparsely to densely hairy, rarely glabrous, indehiscent or rarely dehiscent (in M. hispidum).
1 per mericarp, glabrous.
= 6.
Malvastrum coromandelianum
Malvastrum
Malvastrum coromandelianum is a widespread weed and the most common species in the genus; it is apparently native from Texas to Argentina. The introduced and widespread form has simple hairs on the adaxial surface of the leaf, while the native form has stellate hairs on that surface. Both forms are found in Texas. The species historically has been introduced in ballast in Alabama, Massachusetts, Pennsylvania, and New Jersey, but did not persist.
Subspecies coromandelianum occurs in the flora area and is a widespread weed in tropical and warm-temperate areas worldwide; the other two subspecies occur only in South America and on the Galapagos Islands.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Two or three species of Malvastrum have been widely introduced worldwide in tropical and warm-temperate regions; none is usually cultivated; several are considered to be quite weedy. At least one species (M. coromandelianum) has some medicinal use.
Species 15 (6 in the flora).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Mericarps unornamented or with 1 small apical mucro/cusp to 0.2 mm | → 2 |
1. Mericarps with 1–3 apical cusps 0.1–2.3 mm | → 4 |
2. Mericarps dehiscent, separating into 2 valves, edges of fruit rounded, mucro/cusp absent; inflorescences axillary solitary flowers; leaf blades lanceolate to linear-lanceolate, at least 3 times longer than wide; temperate c United States. | M. hispidum |
2. Mericarps indehiscent, not separating into valves, edges of fruit angled, minute mucro/cusp usually present; inflorescences dense, terminal spikes, sometimes axillary solitary flowers below spikes; leaf blades ovate-lanceolate to ovate, sometimes narrower toward branch tips, usually 1–2 times longer than wide; warm-temperate to subtropical areas | → 3 |
3. Leaves and stems with usually dense, 5–12-rayed, often tufted, stellate hairs; inflorescences dense terminal spikes 3–10 cm. | M. americanum |
3. Leaves and stems with sparse, 3–6-rayed, appressed, bilateral and stellate hairs; inflorescences solitary flowers, axillary or congested or loose terminal spikes 1–2 cm. | M. corchorifolium |
4. Mericarps 2-cusped, cusps conspicuous, distal (pointing away from fruit axis); stems erect, branched usually in distal 1/2; stem hairs not lepidote, 4–8-rayed, radially symmetric; filament tubes puberulent. | M. bicuspidatum |
4. Mericarps 3-cusped, cusps conspicuous or minute, 1 halfway between proximal and distal ends of top surface, 2 distal; stems erect or ascending to decumbent, branched in proximal 1/2; stem hairs sublepidote and 6–10-rayed, or appressed and 2–4-rayed, stellate hairs sometimes mixed with simple hairs, 4-rayed hairs distinctly bilateral; filament tubes puberulent or glabrous | → 5 |
5. Mericarp mucros/cusps 0.1–0.4 mm; 2-fid floral bracts usually present; filament tubes sparsely puberulent. | M. corchorifolium |
5. Mericarp mucros/cusps 0.5–2.3 mm; 2-fid floral bracts absent; filament tubes glabrous | → 6 |
6. Stem hairs sublepidote (stellate-lepidote), 6–10-rayed; mericarps with 1 prominent medial-apical cusp 1.5–2.3 mm and 2 contiguous, flattened, obtuse cusps 1 mm at distal margins. | M. aurantiacum |
6. Stem hairs not sublepidote, 2–4-rayed, bilateral hairs; mericarps with 1 prominent medial-apical cusp 1–2 mm and 2 divergent distal-apical cusps 0.3–1 mm. | M. coromandelianum |
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