Curarea
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Authority
Barneby, Rupert C. & Krukoff, Boris A. 1971. Supplementary notes on American Menispermaceae. VIII. A generic survey of the American Tricilisisae and Anomospermeae. Mem. New York Bot. Gard. 22: 1-89.
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Family
Menispermaceae
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Scientific Name
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Description
Latin Diagnosis - Frutices scandentes, Chondrodendro habitu praesimiles, foHorum lamina palmatim 3-9-nervia inferne dense minutim velutino-tomentella. Inflorescentiae [male] et [female] aut cauliflorae aut e ramulorum annotinorum axillls emissae paniculato-racemosae, [female] quam [male] simpliciores nunc in racemum fere simplicem reductae. Flos i : sepala firma extus tomentella exaete 6, 2-seriata, exteriora 3 minuta, interiora majuscula (juniora valvata) ad anthesin apice subpatula sed minime recurva; petala 6 membranacea obovata exunguiculata sepalis interioribus breviora, stamina laxe nidulantia haud amplectentia; androecii 6-meri filamenta inter se libera erecta recta saepissime ± clavata, antherarum thecis lateralibus terminalibus connectivo angusto separatis sed non superatis, rima longitrorsus dehiscentibus. Flos [female]: sepala maris, interdum bracteolis supranumerariis subtenta; petala 3, cum sepala majora alterna, subchartacea; staminodia 0; carpella 3 stylo subulato non linguiformi terminata. Receptaculum floris [female] post anthesin sub utraque carpella horizontaliter in carpophorum ± elongatum typamni- vel stipitiformem productum, carpophoris 3 ab ipso basi inter se liberis. Drupa in summo carpophoro sessilis demum abscissione decidua, ambitu oblongo-obovoidea; semen hippocrepiforme embryoque Triclisiearum, endocarpi testa tenui, chartaceo, sublaevi.
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Discussion
menispermaceum tribui Triclisieis juxta Sciadoteniam Miers et Chondrodendron R. & P. (cum quo hactenus confusum) referendum, a Chondrodendro sens, restrict, flore i 6- nee pluri-sepalo, sepalis interioribus nee petaloideis nee supra medium reflexo-patulis, flore 9 3- nee 6-carpellato, et imprimis drupa estipitata carpophore (cum receptaculo continuo) elevata et ab eo matura articulata diversissimum. Genus nostrum cum Sciadotenia ut videtur minus affini quoad drupam carpophoro elevatam demum deciduam quadrat sed sepalis utriusque sexus exaete 6 biseriatis, carpellis 3 nee 6-12, carpophorisque a receptaculo abrupte stellatim divergentibus ab ipso basi inter se liberis (nee angulo angusto umbellatim adscendentibus basi ± concretis) procul abstat.
Spp. 4, austro-americanae intertropicae. Generitypus: Curarea toxic of era (Weddell) Barneby & Krukoff.
The concept of Chondrodendron formulated in the revision of 1938 (Brittonia 3: 11-25) was a great advance over that of preceding workers, for it brought together into one group a miscellany of related taxa that had been described not only in Chondrodendron, but also in Cocculus, Abuta, Sciadotenia, and Detandra; at the same time it went far to clarify the synonymy and characterize the component species. Its weakness, unavoidable at that date for lack of fruiting material, lay in its reliance on staminate inflorescence reenforced by a characteristic leaf-pubescence (indument of extremely fine and short hairs clothing the back of the leaf-blades with a felt so close that individual trichomes often cannot be distinguished except under magnification of at least 20 diameters). Of course even at that time there was already apparent from the staminate plants an abrupt cleavage into two groups different in details of perianth. In the first group, which includes C. tomentosum, the generitype of Chondrodendron, and two other species, the perianth is multiseriate, with six or sometimes 12 of the inner scales membranous and petaloid, spreading at anthesis or finally reflexed, so as to present a simulated "corolla." In the second group, of which Chondrodendron toxicoferum and C. candicans are the oldest described members, the perianth outside the true petals is composed of only two sets of three, firm, obviously sepaloid scales. The flower resembles that of Abuta superficially, although differing importantly in the valvate (not imbricate) vernation of the three inner sepals. These differences in the staminate flower are now found to be correlated with a fundamental difference in the fruits. The pistillate flower of genuine Chondrodendron conceals within several cycles of sepals six carpels. As the fruit ripens, the receptacle swells to a globose head bearing six (or by abortion less numerous) fruits that are technically sessile, and finally disjoint leaving on the head of the receptacle a ring of six depressed circular scars. A remarkable feature of the drupe is the fact that it is narrowed at base into a neck-like stipe; but this stipe is part of the drupe and structurally continuous with the dilated part that encloses the nut. The pistillate flower of the second group, here raised to generic status as Curarea, has like the staminate flower only six sepals, arranged in two cycles, the outer much the smaller. Within are found three petals alternating with the inner sepals and within these three carpels, each opposite a major sepal. Anthesis past, the receptacle dilates into three rays or carpophores, in C. toxicofera clavate, either straight or incurved distally; in C. candicans shorter and drum-shaped, each bearing aloft a sessile, eventually disjointing drupe. Superficially the ray derived from the receptacle of Curarea resembles the stipe of the Chondrodendron drupe, but they are not homologous, the abscission layer between the receptacle and the fruit being in the former at summit of the carpophore, in the latter at the foot of the stipe.
The carpophore of Curarea is formed in much the same way as that of Sciadotenia, which has been long known. In Sciadotenia, however, there are always at least six carpels; and the rays of the receptacle ascend at a narrow angle like the spokes of a half-closed umbrella and are united for at least a short distance into a common column. The staminate flower of Sciadotenia resembles that of Chondrodendron more closely than that of Curarea, being composed of many cycles of sepals. The endocarp of Sciadotenia is intricately incised-veiny and more or less engraved between the incised veinlets. Endocarps of Curarea are exceptionally thin-walled, papery, and smooth externally.
The perfect correlation of major differential characters in the perianth and fruits of Curarea and Chondrodendron indicate a fundamental discontinuity between the two groups. In the context of tribe Triclisieae they appear fully distinct genera.
While the general similarity in foliage of Curarea and Chondrodendron might be thought to involve a great difficulty in assigning sterile material to the correct genus, this is not really the case. In the leaf of genuine Chondrodendron the costa gives rise to more than one, sometimes as many as four pairs of major incurved-ascending secondaries, the first of which arises from below the middle of the blade; and the margin of the blade itself is nearly always undulately crenulate. In Curarea there is only one pair of major secondaries arising from above the middle of the blade, and the margins are (unless damaged) essentially plane and entire. Thus the two genera can be distinguished at all stages of growth, whether sterile (seedling or adult) or bearing either flowers or fruits.