Malvastrum coromandelianum |
Malvastrum bicuspidatum |
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common false mallow, three-lobed false mallow, threelobe false mallow |
shrubby false mallow, Sonoran desert false mallow |
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Habit | Herbs, annual or perennial, 0.2–0.6(–1) m, with 1 main stem, freely branching in proximal 1/2. | Herbs, perennial, or subshrubs, (0.4–)1–1.5 m, sparsely horizontally branched, usually with 1 main stem and usually unbranched secondary branches in distal 1/2. |
Stems | erect or decumbent, hairs scattered, appressed, bilateral, (2–)4-rayed, swollen-based, not sublepidote, hairs 1–3 mm. |
erect, canescent, hairs radially symmetric, appressed, not lepidote, with both larger (4- or)5-rayed hairs and minute 4–8-rayed stellate hairs, sometimes shed in age. |
Leaves | 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, narrowly lanceolate, subfalcate, 5–6 × 1 mm, apex acuminate; petiole 10–25(–70) mm; blade wide-ovate to ovate-lanceolate to nearly lanceolate on distal stem, unlobed, usually 3–5 × 1.5–3 cm, 1.3–1.7 times longer than wide, 2.5–3.5 times longer than petiole, base usually rounded to wide-cuneate, margins dentate to sharply dentate, apex acute to acuminate, surfaces stellate-hairy, hairs 4–8-rayed, adaxial surface also with simple hairs. |
Inflorescences | axillary, solitary flowers, flowers sometimes congested towards branch tips; floral bracts absent. |
axillary solitary flowers at first, later elongated terminal racemes, flowers sometimes appearing clustered on reduced racemes, these terminating each branch; floral bracts 2-fid, 4 × 2 mm. |
Pedicels | 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. |
0.5–2 mm, increasing by 0.5–1 mm in fruit; involucellar bractlets adnate basally to calyx for 1–2 mm, narrowly lanceolate to lanceolate, subfalcate, 4–6 × 0.5–1 mm, 1/2 length of calyx lobes, apex acute. |
Flowers | calyx connate 1/4–1/2 its length, rotate, 6–8 mm, to 7–9 mm in fruit, surface hairy, hairs sparse, tufted, stellate, 2–6-rayed, and few, simple, marginal hairs mixed with minute, dense, stellate, 5–8-rayed hairs; corolla wide-spreading, yellow to orange-yellow, 15–18 mm diam., petals obovate, slightly asymmetrically lobed, 6–8 × 7 mm, exceeding calyx by 3–4 mm; staminal column 2–3 mm, stellate-puberulent; style 9–12-branched. |
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Seeds | 1.5–2 mm. |
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Schizocarps | 5.5–8 mm diam.; mericarps tardily shed from calyx, 9–12, 3–4 × 1.8–2 × 1 mm, conspicuously notched, without proximal cusp or with small mucro to 0.1 mm and with 2 conspicuous divergent distal-apical cusps (0.5–)1–1.5 mm, dorsal surface hirsute, hairs simple, rigid, 0.1–1 mm, mixed with simple and stellate, smaller hairs, lateral faces ± glabrous, conspicuously ribbed and thickened. |
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2n | = 24. |
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Malvastrum coromandelianum |
Malvastrum bicuspidatum |
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Phenology | Flowering spring–frost at northern limit as an annual (cold-sensitive), nearly year-round when sufficiently wet and warm as a perennial. | Flowering early–mid spring after winter rains and again in late summer–fall after rains. |
Habitat | River floodplains and banks, disturbed areas, often in alkaline soil | On slopes in arid to semi-arid regions, primarily in dry shrublands in the Sonoran Desert |
Elevation | 0–100 m [0–300 ft] | 30–1300 m [100–4300 ft] |
Distribution |
FL; LA; TX; Mexico; Central America; West Indies; South America (to Argentina) [Introduced worldwide from Tropics and subtropics to warm temperate zones]
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AZ; Mexico (Baja California Sur, Chihuahua, Durango, Sinaloa, Sonora)
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Discussion | 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.) |
Subspecies bicuspidatum is the northernmost representative of Malvastrum bicuspidatum, in sect. Tomentosum S. R. Hill, a primarily Central and South American group of five similar species found mainly in arid regions locally from Arizona south to Paraguay and Brazil; the other three subspecies, subsp. campanulatum S. R. Hill, subsp. oaxacanum S. R. Hill, and subsp. tumidum S. R. Hill, are found in central and southern Mexico and differ by their generally shorter cusps, thinner-walled, non-ribbed and even somewhat leathery mericarps, and usually by more congested racemes. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 6, p. 297. | FNA vol. 6, p. 296. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Malva coromandeliana, M. lindheimerianum | M. tricuspidatum var. bicuspidatum |
Name authority | (Linnaeus) Garcke: Bonplandia (Hanover) 5: 295. (1857) | (S. Watson) Rose: Contr. U.S. Natl. Herb. 12: 286. (1909) |
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