Monographs Details: Rhynchospora dissitiflora Steud. ex Boeckeler
Authority: Maguire, Bassett. 1972. The botany of the Guayana Highland--part IX. Mem. New York Bot. Gard. 23: 1-832.
Family:Cyperaceae
Description:Distribution and Ecology - Distribution. The Andean region in western Venezuela, Peru, and Bolivia; sporadically found in wet grassy slope at altitude of 2000-3000 m. VENEZUELA. Mongas: Cerro Negro, above La Sabana de las Piedras, NW of Caripe, 1500-2180 m alt, Steyermark 62110 (F, NY); Sucre: Cerro Turumuquire, between headwaters of Río Colorado and summit of southern peak, 2200-2400 m alt, Steyermark 62635 (F, NY); Merida: Timotes, Vogl 399 (M). COLOMBIA. Cauca: Cerro Plateado, 2400 m alt, Hurtado & Hutter 1345 (NY, US), Cordillera Occidental, San Antonio to San Jose, bushy bank at 2200-2400 m alt, Pennell & Killip 7276 (GH, NY, US); Dept. Norte de Santander: Cordillera Oriental, región del Sarare, between Alto del Loro and Alto de Santa Inés, 1800-2200 m alt, Cuatrecasas et al 12486 (COL, F). PERU. Huanuco, Central Andean Cordillera, Mirador, near Chanchao, 2400 m alt, Ynes Mexia 7767 (B, NY, US), Tatanara, Lechler 2525a (B, K). BOLIVIA. Unduavi, 10,000 ft alt, Rusby 82 & 83 (K, NY), near Apolo, 6000 ft alt, R. S. Williams 1654 (NY).

Discussion:

Fig 8E-I.

Rhynchospora boliviensis C. B. Clarke, Kew Bull. Add. Ser. 8: 37 & 118. 1908. Syntype. Bolivia, Unduavi, 3000 m alt, Rusby 82 (K, NY) & 83 (lectotype K, NY). Syn nov.

Rhynchospora culmenicola Steyermark, Fieldiana Bot. 28(1): 41, f. 6 B. 1951. Type. Venezuela, Monagas, Cerro Negro, Steyermark 62110 (F, holotype; NY). Syn nov.

Type. Peru, Tatanara, Lechler 2525a (B!).

Having examined the type collections of R. boliviensis and R. culmenicola, I am unable to keep these two species distinct from R. dissitiflora. Schultze-Motel (1960) correctly placed R. culmenicola of Venezuela in the neighborhood of Peruvian R. dissitiflora. When R. culmenicola is compared with R. dissitiflora, as was done by Schultze-Motel, the former plant tends to be slightly taller (30-40 vs 10-25 cm in height) with broader leaf-blades (1 to 1.5 vs 0.5-0.75 mm in width) and longer spikelets (5-6 vs 4-4.5 mm in length). The style-base in R. culmenicola appears to be slightly longer than that of R. dissitiflora at 1.2-1.4 mm vs ca 1 mm in length. However, a series of Bolivian collections cited above show that all of the above measurements not only form continuous ranges but also are not always united. For instance, in Pennell & Killip 7276, the spikelets are only 4 mm long, but the leaf-blades are as wide as 1.5 mm. In the collections of Rusby, the style-bases range from 1.0 to nearly 2 mm in length, but other characters do not at all show any evidence that Rusby’s collections involve two different taxa.

Rhynchospora dissitiflora is most closely related to another Andean species, R. lechleri, in its aphyllopodic habit, puberulent leaf sheaths, and the shape of spikelets. However, sharp differences exist between the two species in the details of inflorescences and achenes in addition to the fact that R. lechleri always has much broader leaf-blades as noted by Kükenthal. The inflorescences of R. dissitiflora are spicate with obliquely ascending sessile spikelets disposed on a slender pendant axis in contrast to the racemose and occasionally few-branched ones with short-peduncled divergent spikelets in R. lechleri. The spikelets in the former are lightly brown, while in the latter they become deeply brown to purple-brown at maturity. In R. dissitiflora its rhombic orbicular body of achenes is cancellated by seven to nine rows of transversely oblong cells, and the apiculate apex of achenes is visible below the truncate base of beak, whereas in R. lechleri the rather elliptic body of achenes is cancellated by 19 to 22 rows of nearly isodiametrical hexagonal cells, and the shallowly bilobed base of beak completely hides the apex of achene body. Furthermore, in the former the achene lacks hypogynous bristles or bears only the very short rudimentary ones, but in the latter three or four elongated bristles much surpass the achene body.

Distribution:Venezuela South America| Peru South America| Bolivia South America| Colombia South America|