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Published In: Species Plantarum 1: 104. 1753. (1 May 1753) (Sp. Pl.) Name publication detailView in BotanicusView in Biodiversity Heritage Library
 

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

 

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2. Diodia virginiana L. (large buttonweed)

D. virginiana var. attenuata Fernald

Pl. 545 c, d; Map 2534

Plants annual, perhaps sometimes short-lived perennial herbs. Stems 20–40(–80) cm long, prostrate or loosely ascending from a spreading base, sparsely to moderately pubescent with short or sometimes longer, straight to wavy hairs. Stipules 2.0–4.5 mm long, the bristles 3–7 on each side, variously 2–7 mm long. Leaf blades 1.2–7.0 cm long, 2–15 mm wide, narrowly elliptic to oblong-lanceolate, angled at the base, angled to a sharply pointed tip, the margins minutely pubescent with stiff, spinescent hairs, flat, the surfaces glabrous short-hairy, the undersurface finely glandular-hairy along the midvein, the venation with the midvein and usually 2–4 pairs of pinnate, secondary veins visible. Flowers solitary or paired in the leaf axils, produced at most of the nodes. Calyces deeply 2-lobed, the lobes 2–8 mm long, lanceolate to triangular, often unequal. Corollas 10–13 mm long, bright white, externally glabrous or nearly so, internally bearded in the throat with the pubescence usually extending onto the lobes, the tube 6–7 mm long, the lobes 5–6 mm long, lanceolate. Styles 2-branched, with long, linear stigmas. Fruits 6–7 mm long, 4–5 mm wide, ellipsoid to broadly ellipsoid, with well-developed longitudinal ridges on the sides, becoming corky, eventually splitting longitudinally into halves. 2n=28. June–September.

Scattered in the Mississippi Lowlands Division and the southern portion of the Ozarks north locally to Lincoln and Hickory Counties (eastern [mostly southeastern] U.S. west to Kansas and Texas). Margins of ponds, lakes, and sinkhole ponds, bottomland prairies, mesic swales of sand prairies, fens, banks of streams and rivers; also levees, ditches, roadsides and moist, open, disturbed areas.

The corky fruits of this species apparently float and are probably dispersed at least in part by water. As in most weedy plants growing in seasonally wet sites, the plants are notably variable in overall size as well as the sizes of the leaves and stipules. And, as in most Rubiaceae, there is a range of variation in pubescence among different plants. Noticeably hairy plants have been called f. hirsuta (Pursh) Fernald.

 


 

 
 
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