Arthrostylidium scandens McClure
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Authority
Maguire, Bassett & Wurdack, John J. 1964. The botany of the Guayana Highland--Part V. Mem. New York Bot. Gard. 10: 1-278.
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Family
Poaceae
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Scientific Name
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Description
Latin Diagnosis - Culmi "scandentes, usque ad 8-metrales," internodiis . . . nodis . . . vaginis (omnibus desideratis) ; rami (partes incompletae tantum ramulas ferentes suppetunt) elongati, graciles, semel ramosi, internodiis glabris nitidisque; foliorum vaginae crassae, supra medium nervoso-striatae carinataeque, glabrae vel glabrescentes, auriculis subobsoletis, setis oralibus crebris, crassis, pallidis, glabris vel asperulis, usque ad 10 mm longis, apice gracillimis fragilisque demum diffractis, ligula interior brevissima vulgo non exserta, ligula exterior glabra, nitida, apice emarginata vel undulans, margine integra vel minutissime ciliolata; foliorum laminae usque ad 18 cm longae et usque ad 35 mm latae, lanceolatae vel oblongo-lanceolatae, apicem versus obtusulum subito acuminatae basi in petiolum crassum usque ad 8 mm longum omnino glabrum inaequaliter rotundatae, paginis utrisque dempto apice hispidulo glabrae, costa subtus tantum basin versus manifesta, nervis secundariis tertiariis vix distinguendis, venulis transversis non manifestis. Inflorescentia vel axillaris vel ramos foliiferos terminans subspicato-racemosa, pedunculo vix exserto, rhachi usque ad 30 cm longa gracili, omnino glabra, passim papillulosa, tereti, supra insertionem pedicellorum sulcata, bracteis pedicellos subtendentibus minutis vel obsoletis, pedicellis rarissime approximatis vulgo 2-3 cm sese distantibus, plerisque ca. 0.5 mm longis nonnullis brevioribus, semicylindratis adpressis, bicarinatis, carinis ciliolatis alibi glabris; spiculae antrorsae, juveniles teretes arctaeque, maturitate compressiusculae hiantesque, mox diffractae pleraeque 5-flores, floscula suprema ad lemma sterile valide involutum subsetiforme reducta; rachillae segmentis compresso-clavatis omnino glabris nitidisque, inferioribus, non medium paleae attingentibus, superioribus medium paleae excedentibus, infra lemmata et supra glumam superiorem disarticulantibus, giumis vacuis vulgo 2, approximatis persistentibus, lanceolatis, hispidulis vel subglabris, pallide stramineis, papyraceis, fragilibus, subaequalibus 5-6 mm longis, carinatis, apice mucronatis; lemma 7-10 mm (rarissime 13 mm) longum, viridi-stramineum purpura pictum, paulum indurate papyraceum fragile (fissile), apicem versus acutum submucronatum carinatumque alibi nervibus submersis plurinerve, dorso omnino glabrum vel superne hispidulum, intus apicem versus minute albo-strigosum; palea lemma aequans vel superans, membranacea, apice comoso obtusa, sulco hispidula, extra carinas glabra invalide paucinervisque, carinis setosula vel glabra; lodiculae 3, hyalinae, enerves, apice parce ciliolatae alibi glabrae, ca. 2 mm longae, diversiformes, anteriores spathulatae, inaequaliter ovato-lanceolatae apice subobtusae, posterior lanceolata; antherae 5.5-6 mm longae primo reticulato-virides brunneo pictae demum pallide brunneae, basi hastatae utrinque apiculatae; apice cornibus 2 brevibus approximatis angustatae, connectivo supra hand producto; ovarium pallidum glabrum; stylus albidus glaber solitarius, supra divisus in stigmatibus 2 dendriformibus, ramis longis gracillimis iterum ramosis. Fructus maturus desideratus.
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Discussion
Type. Locally frequent along stream in moist forest, alt. 600-800 m, below Camp II, Cerro Huachamacari, Rio Cunucunuma, 20 Dec 1950, Amazonas, Venezuela, Bassett Maguire, R. S. Cowan & John J. Wurdack 29957 (holotype US, isotype NY).
The habit of the plant and the nature of the stigmas place this species near A. excelsum Grisebach, which differs most obviously in the inferior length and diameter and the zigzag habit of the inflorescence axis, the more delicate leafsheaths and the narrower leaf-blades.