Rhynchospora trispicata (Nees) Schrad. ex Steud.
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Authority
Maguire, Bassett. 1972. The botany of the Guayana Highland--part IX. Mem. New York Bot. Gard. 23: 1-832.
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Family
Cyperaceae
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Scientific Name
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Description
Distribution and Ecology - Distribution. Very sporadically occurring in wet spots or stream sides in sedge savannas up to 500 m alt. MEXICO: Tabasco: Balancan, Ojó Agua, Matude 3127 (F). CENTRAL AMERICA. Honduras: 2 miles W of Salt Creek O’Neill 9041 (F). VENEZUELA. Barinas: near Barinas, Aristeguieta 1582 (VEN); Guárico; between Santa Rita and Cabruta, Ramia & Trujillo 2769 (MAR); Bolívar: La Gran Sabana, between Fumeremo and El Dorado, Aristeguieta 3745 (VEN), near Kamarata, ca 450 m alt, wet sandy stream bank below high water level, Koyama & Agostini 7560 (NY, VEN). COLOMBIA. La Jagua, Magdalena Valley, C. Allen 543 (F). BRAZIL. Piauí: in campo [without further details], Martius 3232, 3233 & 3234 (M). BOLIVIA. Ixiamas, 1500 ft alt, R. S. Williams 933 (NY), O. Velasco, 200 m alt, O. Kuntze 110 & 121 bis (NY). PARAGUAY. Northern Paraguay, upstream of Río Apa, Hassler 8549 (NY).
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Discussion
Fig 3A-D.
Ephippiorhynchium trispicatum Nees, FI. Brasil. 2(1): 136. 1842.
Rhynchospora guianensis Lindeman & Van Donselaar, Act. Bot. Néerl. 20(4): 440. f. 2d, photo
1. 1971. Type. Suriname, Sipaliwini Savanna, Oldenburger & Norde 133 (U).
Type. Brazil, in campestribus udis provinc. Piahy, Martius 3232 (M, holotype!).
The specimens cited above show a considerable range extension of this rare species, which has hitherto been known only from the Brazilian state of Piauí. Due to superficial resemblance this species has often been confused with pantropic R. triflora, from which it differs sharply in its concave-faced punctulate elongated achenes attaining 5.5-6.5 mm in length in contrast to biconvexed rugose obovate ones 3.5-4 mm long in the latter. Generally in R. trispicata culms and leaves are far more robust than in R. triflora and the lightly brownish oblong spikelets are slightly longer than the dark brown ovate ones at 9 to 12 vs 7 to 9 mm in length (Fig 3).
West Indian R. schmidtii comes closest to R. trispicata. Kükenthal in his monograph (1949) distinguished these two species as follows. In R. schmidtii the culms reaching 1 m or more in height bear two corymbs and broader leaves 5 to 12 mm in width, and the achenes which are 7 mm long are subtended by the bristles much surpassing the achene, whereas in R. trispicata the culms attaining 60 cm in height bear a single cormyb and narrower leaves 3 to 4 mm in width, and the achenes, which are 5.5 mm long, have the bristles only slightly longer than the achene. From my observation, however, this distinction appears to be invalid. In both entities culms and leaves show similar variation range, i e, culms are from 43 to 110 cm in height and leaves in R. trispicata tend also from 4 to 12 mm in width. The length of bristles relative to achenes shows varying combinations and are not constant as keyed by Kükenthal. For instance, in a Paraguayan collection, Hassler 8549, average mature achenes are 5.5 mm long, but are much surpassed by the bristles that reach as long as 8 mm in length, while in Koyama & Agostini 7560 from Venezuela, the larger achenes are 6.5-7 mm long, but all the hypogynous bristles are shorter than the achene body. So far as I have examined specimens only differences between the two taxa consist in the absolute length of the style-base and the hypogynous bristles. In R. schmidtii both the style-base and the bristles are definitely longer than in R. trispicata at 10 to 11 vs 4.5 to 6 mm and 4.5 to 8 vs 9 to 11 mm, respectively. In spite of this minor difference the two taxa are geographically considerably isolated as R. schmidtii is strictly confined to the island of Cuba. Considering the geographical separation in association with the difference in the floral parts, I propose to consider R. schmidtii as a subspecies of the other:
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Distribution
Distribution. Very sporadically occurring in wet spots or stream sides in sedge savannas up to 500 m alt.
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