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Project Name Data (Last Modified On 6/20/2013)

Flora Data (Last Modified On 6/20/2013)
Genus Hieracium L.
PlaceOfPublication Sp. P1. 799. 1753
Note TYPE: H. murorum L.
Description Perennial herbs; stems mostly with long hairs, often also with short hairs, dendritic hairs, glandular hairs, or bristles; sap milky. Leaves often in a basal rosette, cauline leaves present or not, obovate or oblanceolate, entire, dentate or undulate, petiolate or not, sometimes clasping the stem. Inflorescence scapose, paniculate, or rarely of a solitary sessile head; peduncles or pedicels often pubescent, sometimes subtended by narrow bracts. Heads ligulate; involucral bracts in 2-several, graded, imbricate series, the innermost often subequal, nearly valvate; receptacle flat or slightly convex, naked; florets all perfect, all fertile, the corollas yellow (Panama), white, orange or purplish, the ligule short or long, 5-dentate, the tube sometimes apically pubescent, the anthers appendaged, with sagittate or auriculate bases, the style branches slender, papillose, sometimes dark. Achene cylindrical or fusiform, often prominently ribbed or sulcate; pappus of numerous, mostly tawny bristles in 1 series. Pollen echinolophate, usually 3-colporate. Base chromosome number x = 9.
Habit herbs
Distribution Hieracium comprises more than 1000 apomictic "species" in Europe and perhaps a dozen sexual species in the New World north of Colombia.
Note In Panama, species of Hieracium may be recognized by their stout, long, tawny hairs and their inconspicuous, ligulate corollas.
Common Hawkweed Hierba del Gavilan
Reference Robinson, B. L. & J. M. Greenman. 1904. Revision of the Mexican and Central American species of Hieracium. Proc. Amer. Acad. Arts 40: 14-24. Zahn, K. H. 1923. Compositae-Hieraceum. In A. Engler (editor), Das Pflanzen- reich IV. 280 (Heft. 79): 1100-1108, 1115-1124.
Key a. Leaves narrow, mostly less than 2 cm wide, more than 7 times as long as wide, the minute teeth conspicuous; achenes columnar to the apex; upland plants. b. Involucral bracts puberulent with small, whitish, eglandular hairs, a few dark, glandular hairs sometimes present, the margins mostly herbaceous; inflorescence much-branched, many-headed; leaves cauline and basal ...... 1. H. absissum bb. Involucral bracts with copious long, black, often glandular hairs, the margin hyaline at both sides and tips; inflorescence crowded, little-branched, few-headed; leaves mostly basal ...... 3. H. irasuense aa. Leaves spatulate, often more than 2 cm wide, mostly less than 7 times as long as wide, the teeth, if present, inconspicuous; achenes tapering in the upper half; lowland plants ...... 2. H. gronovii
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