Monographs Details: Ophiocaryon maguirei Barneby
Authority: Maguire, Bassett. 1972. The botany of the Guayana Highland--part IX. Mem. New York Bot. Gard. 23: 1-832.
Family:Sabiaceae
Description:Latin Diagnosis - Ab affini O. paradoxo Rob. Schomb. floribus pedicello gracili elevatis, petalis (albis) ad anthesin patulis (nec adscendentibus apice conniventibus), foliolorumque nervis secundariis e costa nascentibus magis numerosis (ex utroque latere saepissime 8-13, nec 5-7) abstans. Arbores parvae ad 10 m altae, trunco 8 cm usque diam, praeter inflorescentiae axes pilis ramulosis rufidulis laxiuscule puberulos glabrae, ramulis annotinis fuscis laevibus longitrorsus striatis; folia dimorpha, ea ramulorum fertilium plerumque parvula simplicia, ea ramulorum sterilium maxima imparipinnata 2-3-juga, petiolo incluso ad 6 dm usque longa, petiolo (simplicium) vel petiolulis (compositorum) incrassatis, in sicco rugulosis, ventre canaliculatis 1-1.4 cm longis; laminae coriaceo-chartaceae opacae ovatae obovatae vel oblongo-ellipticae basi late vel anguste cuneatae apice breviter acuminatae, foliorum simplicium 8-18 cm longae, 4-7.5 cm latae, pinnatorum 15-33 cm longae, 7-12 cm latae; venatio omnium pinnata, costa superne impressa inferne cum secundariis incurvo-adscendentibus intra marginem anguste revolutam arcuato-anastomosantibus elevatim prominulis, nervis secundariis utroque latere (7-) 8-13, tertiariis debilibus, reticulo ultimo aperto fere toto immerso; panicula pendula folio simplici (rarius 3-foliolato) suffulta aperte ramosa ambitu anguste pyramidalis, floribus secus ramulos tertiae quartaeque ordinum ± 3-15 mm longos subfiliformes racemosis, pedicellis 0.7-1.2 mm longis bracteam minutam ovato-deltatam muito excedentibus; flores 5-meri glabri; calycis lobuli inaequales imbricati, majores ad 0.8 mm usque longi ovati obtusi margine pallida membranacea suberosula cincti; petala viva alba, sicca flavido-brunnea, paullo inter se inaequalia, ad anthesin stellatim patula plana ovata vel suborbicularia obtusa ventre carina incrassata longitrorsus percursa, minora ad 1.4 mm, majora ad 1.5—1.6 mm longa usque, 1-1.3 mm lata; staminodia imo petalorum majorum basi adnata, cuneata truncata vix 0.4 mm longa; staminum 2 fertilium ± 1 mm longorum filamentum incrassatum de visu ventrali cuneiforme 0.6-0.7 mm longum sub apice truncato fere aequilatum, antheris (connectivo incluso) ante pollen expulsum 1 mm latis, thecis suborbiculares 0.4 mm diam; ovarium glabrum 0.7 mm longum apice breviter 2-dentatum, stigmatibus divergentibus sinu aperto vix 0.1 mm alto separatis; fructus ignotus.

Distribution and Ecology - Distribution. BRITISH GUIANA. Pakaraima Mts, lateritic soil from gabbro, valley of Mahdia River (tributary of Potaro River), way to Mt. Ebini, at 2250 ft (± 675 m) above station, 15 Oct 1951, fl, Bassett Maguire 32114 [holotype, NY (4 sheets); isotypes, F, K, US]; Karakalli-Clump Wallaba bush on lateritic soil, Eagle Mt. [across the Mahdia valley opposite Mt. Ebini, not over 25 km distant], 26 Jan 1943, fr, Fanshawe 1149 (K, 3 sheets + fruits in carpological coll., these not seen).

Discussion:

This remarkable snakenut resembles O. paradoxum, also known only from British Guiana, in its obtuse petals, but differs both in leaf and in organization of the flower. The leaves of O. paradoxum are, so far as known, homomorphic, all pinnately compound, whereas those of O. maguirei are like those of O. heterophyllum (greatly different in its acuminate petals of the Phoxanthus type) of two sorts, large and pinnate only on the barren branches, smaller and simple or trifoliolate on flowering ones. The leaf-blades of O. maguirei are on the average absolutely and proportionately longer, and have 8-11 (not 3-7) pairs of secondary nerves arising from the midrib. The flower of O. paradoxum is sessile or nearly so, its pedicel, if at all developed, remaining concealed by the suffulcrant bract, and the petals ascend at anthesis, forming a cuplike perianth. In O. maguirei the flower is borne on a slender pedicel greatly exceeding the bract, and the petals expand rotately to form a flattened star. All known records of O. paradoxum are from seasonally inundated creek- or river-banks at low elevations, whereas O. maguirei is found on lateritic soils at elevations of 700-800 meters. The two species are both morphologically and ecologically distinct.

The fruiting specimens collected by Fanshawe on Eagle Mountain were recognized by Sandwith as distinct from O. paradoxum and tentatively referred, no doubt because of the dimorphic leaves, to O. heterophyllum, of which the flower, as now known, is entirely different. I have seen only the vegetative parts of this collection, which includes, however, two seedlings aged 2-4 days. The cotyledons are extremely large, rhombic-ovate-acuminate, 5-plinerved, 12-14 cm long. They closely resemble the seedling of Phoxanthus manausensis illustrated by W. Rodrigues32 (1964, p. 7), and provide further evidence of the naturalness of Ophiocaryon sens. lat. Fanshawe noted that the fruit was found on short shoots low on the stem of the tree; it was globose, green, with mucilaginous flesh and a seed ridged along one side.