Hypolytrum spongiosum T.Koyama

Authority

Maguire, Bassett. 1967. The botany of the Guayana Highland--Part VII. Mem. New York Bot. Gard. 17: 1-439.

Family

Cyperaceae

Scientific Name

Hypolytrum spongiosum T.Koyama

Description

Latin Diagnosis - Ab Hypolytro nudo conspicue recedit omnibus partibus monoribus, inflorescentiis congestis sine radiis, fructificationis parte spongiosa cum parte nicigera aequante numquam triplo longiore ad apicem sensim angustata, et squamellis apice lacerato-rotundatis haud acutis.

Species Description - Planta perennis caespitosa. Rhizoma breve, rectum vel ascendens, usque ad 5 cm longum, 3-5 mm crassum, vaginis mortuis brunnescentibus et earum fibris parallelis obtectum; radices validae, brunneae. Folia multa, fascicularia, culmos longe excedentia; laminae lineares, 20-50 cm longae, 2-7 mm latae, tri-costatae, plicato-planae, herbaceae vel demum tenuiter coriaceae, marginibus aut scabrae aut sublaeves, ad apicem acuminatam sensim attenuantes, basi in vaginas fulvas brunnescentesve gradatim transeuntes. Culmi laterales, scaposi, ex axillis foliorum mortuorum enati, nudi, capillacei, ex toto laeves, 20-30 cm alti; vaginae basilares 2 vel 3, aphyllae, summa ad 6 cm longa, cinnamomea, ore oblique secta. Inflorescentia in capitulum terminale congesta, maturitate 1.5-2.5 cm in diametro; bracteae 2-A, breviter foliaceae, 5-17 cm longae, mox reflexae, evaginantes, (ima interdum brevissime vaginans); spicae (3-) 4 ad 10, sessiles vel infreriores fere sessiles, spisse spicatae vel saepe capitatae, in anthesi clavato-obovatae, maturitate crasse ellipsoideae, 8-10 mm longae, 4-5 mm crassae, obtusae, fuscobrunneae. Glumae imbricatae, ellipticae, 1.75-1.9 mm longae, 0.75 mm latae, chartaceae, naviculares, fulvo-brunneae, unicostatac, apice rotundatae. Squamellae laterales 2, liberae, raro ventraliter plus minus connatae, utraque obovata, 1.8-2 mm longa, 1-1.2 mm lata, monandra, hyalina, brunnea, plicata, basi cuneata, apice lacerato-rotundata, costa spinulis multis approximatis divaricatis vel retrorsis eonspicue hispida; antherae 0.5 mm longae. Fructificationes squamellas duplo longiores, lanceolatae, parte nicigera cum dimidio fructificationis totae aequilonga, longitudinaliter grosse rugosa, brunnea, nitidula, basi subito contracta et breviter stipitata, parte spongiosa fluvescente, haud rugosa, interdum lineis minutis punctata, ad apicem acutam gradatim attenuante; stylus ca 1 mm longus, ad dimidium bifidus (stigmata).

Discussion

Type. Northwest base of Cerro Yapacana, swampy area, scrub forest, frequent between savannas II and III, at 125 m alt, Alto Rio Orinoco, Amazonas, Venezuela, Sept 16, 1957, Bassett Maguire, J. J. Wurdack A W M. Keith 41504 (holotype NY).

Hypolytrum spongiosum is well characterized by the peculiar fructifications, which have a large spongy beak extending over the achene-bearing base. Because of this unique fruiting structure H. spongiosum could be referred only to H. nudum. The two species are, however, quite dissimilar to one another not only by the shape of the fructification but also in some vegetative characters. In H. spongiosum the capillary culms with a congested, head-like inflorescence are always surpassed by the long leaves, whereas in H. nudum the relatively robust culms with an open corymbose inflorescence conspicuously exceed the leaves. In spite of this clear difference, the anatomical structure of the leaves 17 and the fructifications show a good match suggesting that the two species are a distinct yet phylogenetically a related pair. The fact that both of them exhibit precisely the same pattern of disjunct distribution in the Guayana is particularly interesting. C. B. Clarke has apparently confused Hypolytrum spongiosum with H. strictum, which is quite different from it at least by by globose fructifications which completely lack the characteristic spongy beak. Clarke thus illustrated H. spongiosum in his Illustrations of Cyperaceae, pl. 103, figs. 14-19, under the name of H. strictum.