Vines and Climbing Plants of Puerto Rico and the Virgin Islands

96
Vines and Climbing Plants of Puerto Rico and the Virgin Islands
the phyllaries in 2 series, revolute; corollas yellow,
those of the margin with ligules ca. 1.7 cm long;
anthers dark brown; stigmas yellow, reflexed.
Achenes linear, ca. 10 mm long, compressed, 4angled,
with ascending trichomes on the margins;
pappus of 2 retrorsely barbate setae.
Phenology: Flowering from November to
February.
Status: Native, uncommon.
Distribution: In thickets and disturbed areas
on serpentine soil. Known from Puerto Rico,
eastern Cuba, and Campeche in Mexico. Has been
cited erroneously for Jamaica, based on B. dissecta
(O.E. Schultz) Sherff.
Public forests: Maricao and Susúa.
3. CHROMOLAENA
Commentary: I agree with Greenman in
recognizing this biological entity at the species
level, because it is sufficiently different from B.
reptans (see key). The argument presented by O.E.
Schultz to recognize this entity at the level of
subspecies is based on the variation presented by
the leaves of other species of Bidens, specifically
B. alba (L.) DC.; nevertheless, since the latter
species is not close to B. reptans, the knowledge
of its leaf morphology should not be applied to
taxonomic decisions in B. reptans “sensu lato”
(H. Robinson, pers. comm.). The characters that
are used here to recognize B. urbanii at the
specific level have likewise been used to recognize
B. dissecta (from Jamaica), another species closely
related to B. reptans.
Erect or clambering herbs or shrubs. Stems usually pubescent. Leaves opposite, petiolate; blades
simple, usually trinerved from the base. Capitula homogamous, discoid, with 10-40 flowers, arranged
in corymbiform cymes. Involucre cylindrical; phyllaries deciduous, overlapping in 4-7 series. Flowers
bisexual; corollas actinomorphic, tubular, shortly 5-lobed, the lobes usually papillose or glandular;
stamens 5, the anthers inserted, connate; ovary inferior, the style filiform, with two linear stigmatic
branches, elongate, exserted, usually with a sterile papillose appendage. Fruit a turbinate achene,
usually with 5 longitudinal ribs; pappus with ca. 40 filiform bristles without scales. A genus of 166
species distributed from the southern United States to southern South America, including the Antilles.
1. Chromolaena borinquensis (Britton) H. Rob.,
Phytologia 20: 199. 1970.
Fig. 34. A-D
BASIONYM: Osmia borinquensis Britton
SYNONYM: Eupatorium borinquense (Britton) B.L. Rob.
Clambering shrub, slightly woody, much
branched, 1.5-2.5 m in length. Stems cylindrical,
glabrous, and smooth. Leaves opposite; blades 3-
5 × 0.5-2 cm, chartaceous, deltate-lanceolate or
narrowly lanceolate, 3-nerved from the base, the
apex acuminate, the base cuneate or rounded, the
margins with a marginal vein, revolute, remotely
dentate-serrate; upper surface glabrous, with the
venation sunken; lower surface glabrous,
glandular-punctate; petioles 2-5 mm long,
glabrous. Capitula numerous, arranged in
corymbiform cymes; peduncles 1-2 cm long;
involucre cylindrical, 0.5-1 cm high; phyllaries
green, in 5 series, the outer much shorter than
the inner, ovate, glabrous. Corollas pale violet,
tubular, ca. 5 mm long, glabrous; anthers almost
white, stigmatic branches pale violet. Achenes
cuneiform, 3.5-4 mm long, triangular in cross
section, glabrous, black, with the margins white;
pappus of numerous white barbate setae, 3-3.5
mm long.
Phenology: Flowering and fruiting from
November to April.
Status: Endemic to Puerto Rico, uncommon.
Distribution: On slopes of forests or thickets
in the zone of mogotes.
Public forest: Río Abajo.