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

Flora Data (Last Modified On 6/6/2013)
Genus Baccharis L.
PlaceOfPublication Gen.Pl.,ed.5. 370. 1754.
Note TYPE: B. halimifolia L.
Description Dioecious trees or shrubs, rarely herbs, erect or sometimes scandent or decumbent, mostly glabrate and often resinous. Leaves alternate (in Panama), simple, coriaceous or subcoriaceous, the venation pinnate, digitate or with few parallel nerves running to the apex, in some species reduced to thorns or scales or wanting and the stems alate with leaflike, sometimes jointed tissue. Inflorescences mostly somewhat compacted panicles, rarely solitary, racemose or spicate, the pistillate inflorescence usually larger than the staminate. Heads discoid with many florets, the pistillate heads larger than the staminate; involucral bracts imbricate in several unequal and often unlike series, indurate, the margin sometimes hyaline, apically erose, the midvein obsolete near the base; receptacle flat, convex or conical, mostly naked but in the pistillate heads sometimes paleaceous, usually muricate or verrucose, sometimes alveolate; pistillate florets slender to capillary, the corolla inflated at the base and tapering upwards, apically truncate, erose, or with a minute ligule, shorter than the involucre, the style well exserted, linear- oblong to linear, papillose-stigmatic, the ovary fertile; staminate florets tubular, the corolla clearly differentiated into a campanulate limb divided half-way or more into 5 lobes, the anthers basally obtuse or auricled, the appendages narrow, the style branches various but without manifest appendages, the ovary reduced or rudimentary, sterile. Achene cylindrical or somewhat compressed or angled;
Habit trees or shrubs, rarely herbs
Description pappus of fine, often strigulose bristles in 1 or 2 series, sometimes twisted or crinkled and expanded at the apex, colored in some species, that of the fertile achene exceeding the involucre, that of the staminate (sterile) achene not exceeding the styles.
Note The genus Baccharis may be distinguished in Panama by its coriaceous leaves and often resinous twigs and foliage, by its essentially unisexual heads (an occasional floret of the opposite sex may be present), by the basal enlargement of the pistillate corolla, and by the deeply divided staminate corollas.
Distribution Baccharis is a large American genus with some 400 species most abundantly represented in South America.
Note In Colombia 32 species are recognized (Cuatrecasas, 1969) while in Panama there are but two. Baccharis is thought to have evolved from Conyza or some other member of the Astereae by suppression of the bisexual character. When the genus is revised for South America as a whole, several distinct genera may be separated from the present circumscription of Baccharis. Aristeguieta (1964) records that some species are useful in reforestation in Venezuela, and in Colombia some species are used on a local scale as dyestuffs. The foliage of some species is toxic to livestock, but the plant is unpalatable. In the Old World, particularly in India and Australia the Caribbean species, B. halimifolia L., has become naturalized as a noxious woody seed.
Key a. Plants glabrous except on emergent parts and petioles, young parts resinous; staminate involucral bracts more than 1.5 mm broad, the florets ca. 6 mm long, the limb lobed about halfway down, the sterile ovary longer than broad; pistillate receptacle with short to minute persistent paleas, usually blackening, the corollas inflated in the lower 1/3 portion ...... 1. B. pedunculata aa. Plants minutely puberulent with fine, arachnoid hairs, mostly not resinous; staminate involucral bracts less than 1.2 mm broad, the florets ca. 4 mm long, the limb lobed nearly to the base, the sterile ovary disclike, shorter than broad; pistillate receptacle with elongate, deciduous paleas, not blackening, the corollas inflated in the lower '/5 portion ...... 2. B. trinervis
 
 
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