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Published In: Species Plantarum 2: 687. 1753. (1 May 1753) (Sp. Pl.) Name publication detailView in BotanicusView in Biodiversity Heritage Library

Project Name Data (Last Modified On 8/25/2017)
Acceptance : Accepted
Project Data     (Last Modified On 7/9/2009)
Status: Introduced


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1. Alcea rosea L. (hollyhock)

Althaea rosea (L.) Cav.

Pl. 450 c, d; Map 2043

Plants biennial or perennial herbs, variably pubescent throughout with smaller stellate hairs and coarse simple hairs (these mostly in fascicles), somewhat roughened to the touch. Stems 100–300 cm long, mostly erect, usually unbranched. Leaves long-petiolate, the blades 2–10 cm long, broadly ovate to circular or kidney-shaped in outline, at least the lower leaves shallowly 5- or 7-lobed, the base rounded to shallowly cordate, pointed to more commonly rounded at the tip, the margins shallowly scalloped or toothed. Stipules shed before leaf maturity, 3–9 mm long, lanceolate. Flowers solitary or in small clusters in the leaf axils, often also in a terminal spikelike raceme, the bractlets subtending the calyx 6–9, conspicuous, 9–12 mm long, fused toward the base, the lobes broadly triangular. Calyces 16–24 mm long, cup-shaped at fruiting, the sepals fused in the basal 1/3–1/4, the lobes triangular. Petals 35–50 mm long, the tips broadly rounded to truncate or shallowly notched, the margin otherwise entire or nearly so, white to dark purplish black, often pink. Stamens numerous, the staminal column 5-angled in cross-section, without a low crown of teeth at the tip, the anthers yellow. Pistils with 18–40 locules, the carpels arranged in a loose apically flattened ring. Styles fused most of their length, each branch with a single linear stigmatic area along the inner side toward the tip. Fruits schizocarps breaking into 18–40 mericarps. Mericarps 4–8 mm long, wedge-shaped, tan to brown, beakless, the dorsal surface with a longitudinal groove, kidney-shaped to nearly circular in profile, the lateral walls thin and smooth but with a reticulate pattern of thickenings toward the dorsal margin, which is angled into a narrow wing, the thin portion shattering irregularly at maturity (the fruit also eventually breaking apart into individual mericarps), 1-seeded. Seeds 3–4 mm long, kidney-shaped, the dorsal portion densely and minutely pubescent with mostly spreading fascicles of hairs, brown. 2n=42. May–September.

Introduced, uncommon and widely scattered in the state (native range unknown but presumably southwestern Asia; widely and sporadically escaped from cultivation in the U.S.). Roadsides, railroads, and open disturbed areas.

Hollyhocks are widely cultivated as ornamentals in Missouri, but rarely become established outside gardens. A large number of cultivars exist varying in plant height, corolla colors, and leaf morphology, including some with doubled corollas, and the few specimens of escaped plants reflect this variability. Some authors continue to maintain Alcea as part of an expanded concept of the genus Althaea, but Zohary (1963a, b) and D. A. Webb (1968), among others, have separated the two groups based on differences in inflorescence and flower structure and size.



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