Mapania steyermarkii T.Koyama
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Authority
Maguire, Bassett. 1967. The botany of the Guayana Highland--Part VII. Mem. New York Bot. Gard. 17: 1-439.
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Family
Cyperaceae
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Scientific Name
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Description
Species Description - Species valde distincta in sectione Pycnocephala; a Mapania macrophylla glumis propriis apice acutis, hvalina, demum deficientibus, et a Mapania insigni fruetubus multo majoribus, bracteis involucrantibus basi non dilatatis facile cognoscenda. Rhizoma breve, eaespitem laxum formans. Folia radicalia elongata, 70-110 cm longa, 2-4.5 cm lata, unicostata, ad apicem longissime acuminatam sensim attenu-antia, margine utringue sursum semilato-scabra, basi sensim angustata, in vaginas 15-20 cm longas rubescentes vel fusco-purpureas antice membranaceas demum deficientes transeuntia; cataphylla pauca concoloria plerumque adsunt. Culmus centralis, ex unico fasciculo solitarius, basi tantum foliatus, follis brevior, 45-65 cm altus, trigonus, 3-5 mm crassus, angulis infra medium obtusiusculis, sub infloreseentia acutioribus et scabriusculis. Caput amplum, terminale, globosum vel paulo depressum, 5-6 cm in diametro, 2.5-3.5 cm altum, flavo-brunnescens; bracteae involucrantes 2 vel 3, foliaceae, (20-) 50-95 cm longae, 2-4 cm latae, basi paulo angustatae, purpureo-fusco-tinctae, evaginantes. Spiculae propriae nume-rosae, desissime congestae, oblongae, apice acutae, 12-20 mm longae, circiter 4 mm latae; glumae propriae multae, spisse imbricatae, hyalinae, demum deficientes, anguste lanceolatae vel lanceolato-oblongae, 9-12 mm longae, ad 1.75 mm latae, ad costam unicam fluvescentes, apice sensim acutae. Spiculae partiales lineares, cum gluma propria sua aequantes, squamellis 4, duabus inferioribus lateralibus oppositis et duabus superioribus dorsiventralibus constructae, tamen plerumque omnes variatim in tubo connatae. Flores staminei 2, uterque monander, ex axilla squamellae lateralis ortus; anthera 3 mm longa. Flos foemineus pistilo nudo tan-tum constructus, terminalis. Fructus late ellipticus raro aliquanto obovato-ellip-ticus, 3.5 mm longus, 2.5 mm latus, faciebus convexis crasse lenticularis, maturi-tate fusco-niger, nitens, ad angulos obtusos saepissime laeviter canaliculatus, apice basique contractus; stylus perlongus; stigmata 2, longa.
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Discussion
Type. Sporadically occurring on wet humus-rich soil by ravine, sheltered by dense tropical forest. Uaipan-tepui, trail between the summit and the base of West Peak, near the headwater of Rio Pul-pul, 1200-1600 m alt, Bolivar, Venezuela Tetsuo Koyama & Getulio Agostini 7506 (holotype NY, isotype VEN). Paratypes. VENEZUELA. Bolivar: Cerro da Danta, northwest of Cerro
Mapania steyermarkii is well characterized by the unique shiny black elliptic fruits. Because of the structure of the partial spikelets it is placed in section Pycnocephala together with M. macrophylla, M. insignis, M. surinamensis, M. pycnocephala, and M. fluviatilis. The large fruits in M. macrophylla are comparable to those of M. steyermarkii, but they sharply differ in the dull surface and ridged (not furrowed) angles. M. insignis also has hyaline glumes that become disintegrated after anthesis, but it differs from M. steyermarkii in the much smaller fruits, which are less than 1 mm long. M. surinamensis, M. pycnocephala, and M. fluviatilis cannot be compared with M. steyermarkii at least in their castaneous or fuscous glumes.