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Published In: Flora Boreali-Americana (Michaux) 2: 214. 1803. (Fl. Bor.-Amer.) Name publication detailView in BotanicusView in Biodiversity Heritage Library

Project Name Data (Last Modified On 8/11/2017)
Acceptance : Accepted
Project Data     (Last Modified On 7/9/2009)
Status: Native


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1. Croton capitatus Michx. (woolly croton, hogwort)

Map 1656, Pl. 377 k–o

Plants monoecious, densely pubescent with short, stellate hairs, the branches 0.4–1.0 mm long, often slightly unequal. Stems 20–90 cm long, often sparsely to moderately alternately branched, but sometimes with a pronounced whorl of branches above the midpoint. Leaves all or mostly alternate, at least the lower and median leaves long-petiolate, the petiole without large, saucer-shaped glands at the tip. Leaf blades 2–12 cm long, lanceolate to oblong-lanceolate, triangular-lanceolate, or triangular-ovate, rounded or less commonly shallowly cordate at the base, rounded to angled or tapered to a bluntly or sharply pointed tip, the margins entire or slightly wavy below the midpoint, the undersurface usually paler than the upper surface. Inflorescences terminal at the branch tips (the uppermost branches sometimes short and these inflorescences then appearing axillary), short, dense, spikelike racemes (often appearing headlike or as dense clusters) with pistillate flowers toward the base and staminate flowers toward the tip. Staminate flowers with the calyx deeply 5-lobed, 0.8–1.2 mm long; the petals 5, 0.8–1.2 mm long, white to pale cream-colored; the stamens (7–)10–14. Pistillate flowers with the calyx 2–4 mm long at flowering, becoming enlarged to 6–9 mm long at fruiting, 6–9-lobed; the petals absent; the ovary 3-locular, the 3 styles each dichotomously lobed 2 or 3 times (the total number of stigmatic branches thus theoretically 12–24 per flower, but in practice mostly 12–16; the second and third order divisions usually well above the style base). Fruits 6–9 mm in length and diameter, nearly spherical, persistently densely hairy at maturity, 3-seeded (rarely 2-seeded by abortion of 1 ovule), dehiscent. Seeds 3.5–5.0 mm long, circular to oblong in outline, sometimes somewhat flattened, the caruncle present. 2n=20. June–October.

Scattered nearly throughout the state but apparently absent from the far northwestern portion (eastern U.S. west to South Dakota and Texas; Mexico). Glades, upland prairies, and sand prairies; also pastures, dry ditches, old fields, fallow fields, farmyards, railroads, roadsides, and open, sandy, disturbed areas.

Steyermark (1963) noted that cattle can become poisoned if they eat hay contaminated with this species, but that they tend to avoid living plants in pastures because of the bitter flavor that renders them relatively unpalatable. Burrows and Tyrl (2001) noted that the diterpenoid esters (croton oils) characteristic of the genus cause inflammation of the digestive tract.

Steyermark (1963) treated C. capitatus as comprising two varieties in Missouri. A third variety recognized by some authors (Johnston, 1958), var. albinoides (A.M. Ferguson) Shinners, grows in Texas and Mexico and differs only slightly from var. lindheimeri in its smaller (less than 4 mm long), more strongly obovate seeds. Johnston (1958) and Webster (1967) suggested, however, that the two taxa in Missouri might better be treated as distinct species. In spite of this, a number of seemingly intermediate specimens exist that appear to justify the use of a lower taxonomic rank. The characters used by Steyermark are also different than those used by Johnston, which may account for some of the ambiguously placed specimens, as Steyermarks use of leaf size and hair color does not appear to separate Missouri materials adequately.


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1 1. Leaf blades with the tip rounded to bluntly or sharply pointed, if pointed then mostly tapered from about the midpoint (occasionally from the lower third in the largest leaves), occasionally rounded but with an abrupt, minute, sharp point; leaves all relatively long-petiolate, even those of the upper leaves; seeds about as long as wide (nearly circular in outline but somewhat flattened in profile), the surface smooth and usually not mottled ... 1A. VAR. CAPITATUS

Croton capitatus Michx. var. capitatus
2 1. Leaf blades with the tip sharply pointed, tapered from near the base; lower leaves relatively long-petiolate, the petioles progressively shorter above the stem midpoint; seeds longer than wide (oblong in outline and sometimes somewhat flattened in profile), the surface finely but faintly roughened and usually mottled ... 1B. VAR. LINDHEIMERI Croton capitatus var. lindheimeri


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