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Published In: Mantissa Plantarum 2: 286. 1771. (Mant. Pl.) Name publication detailView 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. Eclipta prostrata (L.) L. (yerba de tajo)

E. alba (L.) Hassk.

Pl. 278 a–c; Map 1176

Plants annual, sometimes forming mats, with small taproots. Stems 5–75 cm long, spreading to erect, sometimes ascending from a spreading base, sometimes rooting at the nodes, few- to many-branched, with fine longitudinal ridges and grooves, sparsely to densely pubescent with appressed-ascending hairs, especially toward the tip, sometimes glabrous toward the base. Leaves opposite, sessile or with a short, poorly differentiated petiole, the base slightly expanded and wrapping around the stem. Leaf blades 1–10 cm long, narrowly lanceolate or narrowly elliptic to lanceolate or elliptic, unlobed, tapered or narrowly angled at the base, tapered to a sharply pointed tip, the margins sparsely to densely and finely toothed and with short, stiff, appressed hairs, the surfaces sparsely to moderately pubescent with short, stiff, appressed hairs, these usually with a minutely expanded, somewhat resinous, pustular base. Inflorescences of solitary terminal and/or axillary heads or sometimes in small clusters of 2 or 3, the heads appearing short- to long-stalked (the stalks bractless). Heads radiate but sometimes appearing discoid. Involucre 2–5 mm long, 3–5 mm in diameter (becoming broader as the fruits mature), cup-shaped to broadly cup-shaped or slightly bell-shaped, the bracts in usually 2 subequal series (the inner series sometimes slightly shorter than the others). Involucral bracts 10–12, green but with the basal half lighter and prominently several-nerved, mostly ascending at the tip (the outer series sometimes loosely ascending at the tip), narrowly lanceolate to ovate. Receptacle flat to shallowly convex, broadening as the fruits mature, the florets subtended by chaffy bracts, these narrowly linear, awnlike, and shed with the florets. Ray florets 20 to numerous in 2 or 3 series, pistillate (with a 2-branched style exserted from the short tube at flowering), the corolla 1–3 mm long, relatively slender, white, glabrous, not persistent at fruiting. Disc florets 15 to numerous (more than 100), perfect, the corolla 1.0–1.5 mm long, white, the short tube not expanded at the base or persistent at fruiting, glabrous, the mostly 4 minute lobes glabrous. Style branches with the sterile tip short-tapered to a bluntly pointed tip. Pappus absent or a minute rim or crown. Fruits 2.0–2.5 mm long, more or less wedge-shaped to somewhat triangular in outline, 3- or 4-angled, sometimes slightly flattened, the surface usually appearing wrinkled or warty, straw-colored to brown or less commonly black, the tip minutely hairy and usually darker than the rest of the fruit (green when immature). 2n=22. July–October.

Scattered to common throughout the state (eastern U.S. west to South Dakota, Texas, and California, Mexico, Central America, South America, Caribbean Islands, Asia south to Australia; introduced in Hawaii, Canada, and Europe). Banks of streams, rivers, and spring branches, marshes, seeps, and margins of ponds, lakes, sinkhole ponds, and sloughs; also crop fields, fallow fields, ditches, gardens, railroads, roadsides, and moist, open, disturbed areas.

The native distribution of this species is poorly understood as it is a widespread colonizer of disturbed habitats. Eclipta prostrata was long known as E. alba in the literature on New World plants. Koyama and Boufford (1981) discussed the taxonomy of this complex in the context of a proposal to make a minor change in the wording of an article in the International Code of Botanical Nomenclature. They noted that plants growing in the Old World could not be distinguished from those in the New World and that plants from throughout the combined range should be united under the name E. prostrata.



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