Monographs Details: Odontocarya amazonum Barneby
Authority: Barneby, Rupert C. 1972. New and notable Menispermaceae tribe Tinosporeae. Mem. New York Bot. Gard. 22: 137-151.
Family:Menispermaceae
Description:Latin Diagnosis - Ab O. syncretica Barneby foliorum petiolo brevi (3-5 nee 5.5-9.5 cm longo) laminae reticulo clauso (areohs ± 1 nee 1-2 mm latis) et endocarpii minoris 16-18 (nee 20-22) mm longi condylo aperto testaque tenuiori coriacea nee lignea absimilis. Frutices scandentes glaberrimae staturae ignotae, trunco laevi haud exfolianti 1 cm usque diam, ramulis annotinis foliatis atropurpureis longitrorsus sulcatis lenticellatis; foliorum petiolus gracilis 3-5 cm longus ipso apice dilatatus, lamina (sicca) subchartacea utrinque lucida inferne pallidior e basi late cuneato vel subrotundato ovatovel obovato-elliptica, acumine lanceolato apiculato ± 1 cm longo incluso 8-14 cm longa, 4-8 cm lata; venatio primaria ex ipso basi 3-plinervia tunc pinnata, nervis lateralibus primariis mediam laminam fere attingentibus, ut costa gracilibus utrinque sed inferne altius prominulis, costa nervos secundarios utroque latere 3-4 gignenti, venatione tertiaria utrinque subtili prominula, reticuli areolis ultimis ± 1 mm diam; inflorescentiae [male] ignota [female] e trunco aphyllo nascens bis-racemosa glaberrima, axibus primario ad 2 dm usque secundariis (paucis visis) saltem 5-8 cm usque plurifloris, pedicellis fructiferis ±5-6 mm longis 1 mm diam; flores ignoti; drupae (siccae) oblongo-ellipticae 17-19 mm longae 9-10 mm diam exocarpium coriaceum nigricans, mesocarpium mucilagineum haud vel vix adhaerens tenue; endocarpii oblongo-ovoidei basi rotundati apice obscure 3-denticulati 16-18 mm longi 7.5-8.5 mm diam dorso convexi carina longitudinali gracili percursi caeterius haud sculpti sed minutim asperati ventre parum depressi supra medium condylo lineari angustissime tubuloso 7-8 mm longo ±1.1 mm diam excavati (apertura lineari-oblanceolata 0.4-0.7 mm lata) testa coriacea secta 0.2-0.25 mm crassa.

Distribution and Ecology - BRAZIL. Amazonas: on campinarana of plateau between Rio Livramento and Rio Ipixuna, mun. Humayta, basin of Rio Madeira, Nov 7-18, 1934, fr., B.A. Krukoff 7279. Holotypus, NY; isotypi. A, K. Virgin forest on terra firme, Rio Canuma, region of Rio Madeira, Nov 11, 1957, fr, R. L. Froes 33811 (IAN, NY, fragm.).

Discussion:

Fig. 1.

The holotype of O. amazonum, identified in the first instance by Moldenke as Hyperbaena solimoesana [= Anomospermum solimoesanum (Mold.) Krukoff & Barneby], was deliberately passed over at the time of m y revision of the tribe for this reason: the partial inflorescence, bearing ripe drupes, was already separated from the leafy branchlet mounted with it and I could not be sure that the two elements belonged together. The plant collected by Froes on a tributary of the Madeira about 300 k m northwest of type-locality, while fragmentary as far as foliage goes, shows the main axis of a cauliflorous pistillate inflorescence organically attached to a segment of the rope; furthermore an isotype examined recently (A) shows the same connection between fruit and leaf. Taken together, these specimens provide a picture of an odontocarya related to the hitherto rather isolated 0. syncretica, like it (but unlike all other known congeners) in having a bisracemose cauliflorous panicle combined, at least in O. syncretica, with a hexamerous androecium. The leaves of O. amazonum are pinnately veined as those of O. syncretica, although more shortly petioled and more finely reticulate; and the endocarps (Fig. 1) are similar in their nearly smooth outer surface and narrowly tubular condyle immersed in the scarcely depressed ventral face. However, while the condyle of O. syncretica is almost closed externally, and therefore truly tubular, that of O. amazonum opens by a linear slit, appearing externally like a narrow gutter. The only known station for O. syncretica is in the region of the Amazon delta, distant by airline 1200 k m east of Canuma.

It seems likely but by no means certain that the staminate sex of 0. amazonum will eventually be recognized in a confused but historic collection from Rio Taruma near Manaus, Ducke s. n., Jul 25, 1948 (IAN). This collection is confused because it embodies two elements: a leafy branchlet of Abuta (provisionally named by Krukoff & Barneby in Mem. N. Y. Bot. Gard. 22(2):66 as /I. panurensis Eichl.); and a segment of rope with some detached pieces of a staminate panicle at anthesis, both Tinosporeous. The collection is historic because the flowers were described (Moldenke, Bull. Torrey Club 78: 262) and attributed falsely to Anomospermum froesii, of which the true staminate plant is Hyperbaena solimoesana. Ducke's field note describes the inflorescence as cauliflorous and it m a y be assumed that the segment of rope is the stem from which the inflorescence was severed. These flowers have the androecium of sect. Parasomphos, that is of six separate stamens. Unfortunately the inflorescence is now so broken up that the order of complexity cannot be determined. For this reason there is no really firm reason for attributing the plant to O. amazonum, and its final disposition must be held in abeyance.

It will be noted that O. amazonum has certainly once and perhaps twice been mismatched with the leaves or the pistillate form of species belonging to another tribe, although this could have been avoided by close attention to reticulation-patterns of the leaf-blades.