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Published In: Prodromus Systematis Naturalis Regni Vegetabilis 15(2[2]): 686. 1866. (Prodr.) 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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2. Croton glandulosus L. var. septentrionalis Müll. Arg. (sand croton, tropic croton)

Map 1657, Pl. 377 e–g

Plants monoecious, densely pubescent with short, mostly stellate hairs (the upper surface of the leaves sometimes with some of the hairs appearing unbranched or nearly so and spreading), the branches mostly 0.3–0.7 mm long and loosely appressed, but with 1 branch much longer (to 2 mm) and spreading. Stems 15–60 cm long, alternately branched but with some or most of the branches in irregular whorls. Leaves alternate, opposite, or whorled, short-petiolate, the petiole with 1 or 2 large, saucer-shaped (or 2-lipped), white to cream-colored glands at the tip. Leaf blades 1–7 cm long, narrowly oblong to oblong-lanceolate, oblong-oblanceolate, or less commonly oblong-ovate, mostly angled or tapered at the base at the base, mostly angled to a bluntly pointed tip (occasionally rounded or sharply pointed) tip, the margins finely toothed, the undersurface sometimes slightly paler than the upper surface. Inflorescences appearing terminal and between the stem branches, short, dense, spikelike racemes (often appearing as dense clusters) with pistillate flowers toward the base and staminate flowers toward the tip. Staminate flowers with the calyx deeply (4)5-lobed, 0.7–1.5 mm long; the petals (4)5, 1–2 mm long, white; the stamens 7–13. Pistillate flowers with the calyx 1.2–1.8 mm long at flowering, becoming enlarged to 3.5–4.5 mm long at fruiting, 5-lobed; the petals absent; the ovary 3-locular, the 3 styles each deeply 2-lobed (the total number of stigmatic branches thus 6 per flower). Fruits 3.5–5.5 mm in length, 4–5 mm in diameter, nearly spherical, 3-seeded (rarely 2-seeded by abortion of 1 ovule), dehiscent. Seeds 3–4 mm long, oblong-ovate to oblong-elliptic in outline, somewhat flattened and often slightly wedge-shaped, the caruncle present as a small knob. July–October.

Scattered nearly throughout the state but absent or uncommon in the western half of the Glaciated Plains Division (eastern U.S. west to Minnesota, Nebraska, and Texas). Glades, upland prairies, sand prairies, and openings of bottomland forests; also pastures, crop fields, fallow fields, ditches, levees, railroads, roadsides, and open, disturbed areas.

Infraspecific variation in C. glandulosus requires much more detailed study. Numerous varieties have been named in this widespread and variable species, which occurs from North America to South America and in the Caribbean Islands, but a comprehensive summary of variation in the species or even a key to determination of all of the varieties does not appear to exist. Johnston (1958) treated three varieties in Texas. Webster (1967) further noted the existence of several taxa described as species in Florida that are very closely related to C. glandulosus, some of which might better be classified as varieties. Missouri plants apparently correspond to var. septentrionalis, the northernmost phase, which is robust but with relatively small, narrower leaves having relatively sharply toothed margins, small seeds, and moderately coarse, spreading pubescence. Its relationship to the more tropical var. glandulosus, which apparently occurs as far north as Florida, remains to be elucidated. Interestingly, although the variety is considered of conservation concern in a few northern states, it is considered a crop weed in some southeastern states.



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