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Flora of the Venezuelan Guayana

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CLUSIACEAE

7. HYPERICUM L., Sp. Pl. 783. 1753.

by Norman K. B. Robson

Shrubs or perennial (some possibly annual) herbs, branching strict or ± basal, plants glabrous, with pellucid glands. Stem internodes 4-lined, at least when young. Leaves sessile, to ca. 3 cm long, narrowly lanceolate or narrowly elliptic-oblong to linear. Flowers solitary with pseudodichotomous branching, or else numerous in dichasial or monochasial cymes. Sepals 5; petals 5, usually yellow, ± spreading. Stamens ca. 15-50, not visibly grouped; anthers short. Ovary 1-locular, placentation usually parietal, many ovules per carpel; styles 3(4 or 5), papillate, erect to spreading; stigmas narrow to broadly capitate. Fruit mostly a capsule, less often a berry. Seeds numerous; cotyledons small.

Nearly cosmopolitan (most abundant in temperate areas); ca. 420 species, 23 in Venezuela, 3 of these in the flora area.

Key to the Species of Hypericum

1. Herbs with erect to ascending basal branches; stem internodes 2-35 mm long; leaves plane or with margin recurved; flowers in terminal dichasial or monochasial cymes ..... H. thesiifolium

1. Shrubs with upright branches; stem internodes 0.7-2 mm long; leaves plane to incurved; flowers solitary, branching pseudodichotomous ..... 2

2(1). Leaves incurved, the lower surface with impressed midrib, coriaceous, pairs united at base ..... H. marahuacanum

2. Leaves plane, the lower surface with prominent midrib, chartaceous, pairs free at base ..... H. roraimense

Hypericum marahuacanum N. Robson, Bull. Brit. Mus. (Nat. Hist.), Bot. 16: 77. 1987.

Shrub 0.3-1.5 m tall; leaves densely imbricate, deciduous above base without fading; blade 0.6-1 mm wide; stigmas narrow to narrowly capitate. Colombia, Venezuela; 3 subspecies, all in Venezuela, 2 of these in the flora area.

The third subspecies (subsp. strictissimum N. Robson) occurs in the Andes of Venezuela (Mérida) and Colombia (Boyacá).

Key to the Subspecies of H. marahuacanum

1. Glands on lower surface of leaves obscure or apparently absent; sepals 4-6 mm long; styles 2-3.5 mm long; capsule ovoid-ellipsoid ..... subsp. chimantaicum

1. Glands on lower surface of leaves clearly visible; sepals 7-9 mm long; styles 4-5 mm long; capsule narrowly ovoid ..... subsp. marahuacanum

H. marahuacanum subsp. chimantaicum N. Robson, Bull. Brit Mus. (Nat. Hist.), Bot. 16: 80. 1987.

Swampy open tepui meadows, 2100-2500 m; Bolívar (Macizo del Chimantá, Roraima-tepui). Endemic. Fig. 215.

H. marahuacanum subsp. marahuacanum

Shaded streamsides on high-tepui summit, 2500-2800 m; Amazonas (Cerro Marahuaka). Endemic.

Hypericum roraimense Gleason, Bull. Torrey Bot. Club 56: 399. 1929.

Shrub 14-50 cm tall, forming rounded bushes; leaves suberect, becoming brown and deflexed, persistent; blade 1-1.8 mm wide, lower surface with slightly prominent midrib; stigmas broadly capitate. Swampy areas on mostly rocky tepui summit, 2500-2900 m; Bolívar (Roraima-tepui). Guyana.

Hypericum thesiifolium H.B.K., Nov. Gen. Sp. (quarto ed.) 5: 192. 1821 [1822]. Hypericum uliginosum H.B.K., Nov. Gen. Sp. (quarto ed.) 5: 194. 1821 [1822].

Hypericum silenoides auct. non Juss. 1789.

Perennial or maybe sometimes an annual herb, 7-65 cm tall; stems erect or ascending; leaves not imbricate, erect to ± spreading, lower eventually deciduous; blade 0.8-6 mm wide, the lower surface with slightly prominent midrib; stigmas broadly capitate. Moist open habitats, 1200-1300 m; Bolívar (Parupa). Aragua, Distrito Federal, Guárico, Miranda, Táchira, Trujillo; Panama, Costa Rica, Colombia.

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Scientific Comments:
Paul Berry (peberry@facstaff.wisc.edu) or Kay Yatskievych (kay.yatskievych@mobot.org).

 
 
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