Monographs Details: Myrcia platyclada DC.
Authority: Maguire, Bassett. 1969. The botany of the Guayana Highland-part VIII. Mem. New York Bot. Gard. 18: 1-290.
Family:Myrtaceae
Scientific Name:Myrcia platyclada DC.
Description:Distribution and Ecology - French GUIANA. Without locality ["Cayenne"], [Patris?] sn (G-DC, type.Field Mus. neg. 7922); in sylvis praedii D m . Boutin, in territorio Tonnegrande,Richard 98 (P, lectotype oiA. dumosa); ad extremum prati maximi praedii Les Deuxflots dicti, Richard 62 (P, paratype of A. dumosa, Field Mus. neg. 36501); "in ripisfluvii Kourou," Richard 63 (P, type of A. edulis); without locality, Melinon in 1842(P)-

Discussion:

Aulomyrcia diimosa Berg, Linnaea 30: 656. 1861.

Aulomyrcia edulis Berg, Linnaea 30: 657. 1861.

Myrcia dumosa (Berg) Krug & Urb. ex Urb., Bot. Jahrb. 19: 580. 1895.

Myrcia edulis (Berg) Krug & Urb. ex Urb., Bot. Jahrb. 19: 581. 1895.

Aulomyrcia platyclada (DC.) Amsh., Bull. Torrey Club 75: 531. 1948.

Aulomyrcia platyclada var kaieleurensis Amsh., Bull. Torrey Club 75: 532. 1948.

type of Myrcia platyclada (cf Field Mus. neg. 7922), from French Guiana ("Guiana Gallica") according to de Candohe, was a plant with obtusely rounded obovate-cuneate leaves up to about 7 cm long, and somewhat flattened branchlets and peduncles. The hairs of the inflorescence are dibrachiate but often unequahy so, and not very flat or broad. I have not seen any modern specimens hke it from the Guianas, but the collections by Richard, on which Berg based Aulomyrcia dumosa and A. edulis, evidently belong to the same species. As I now understand M . platyclada, it includes West Indian and South American plants that are alike in having relatively stout and somewhat compressed panicle branches; the pubescence is partly of minute, pale or brownish, flat and closely appressed, laterally attached and usually dibrachiate hairs; the midvein is impressed on the upper surface; the leaves vary from obovate to elliptic, but are acuminate more often than not; the buds are glabrous without or with a few hairs at base; the calyx-lobes are 5, pubescent on the inner surface, and the calyx splits to some extent as the flowers open. Modern South American material is from several widely separated localities and conceivably may represent more than the one species.

This interpretation of Myrcia platyclada is the same as that of Amshoff, who had compared "a fragment and a duplicate of the type . . , collected by Patris in French Guiana." Urban, who stated that he had studied Berg's "type" of Aulomyrcia dumosa in Berlin, apparently did not recognize the identity of A. dumosa and M. platyclada, although both were described initially from French Guiana. According to Urban, Myrcia {Aulomyrcia) dumosa occurs on the islands of Guadeloupe, Martinique and St. Lucia; it is also reported by R. O. Wihiams from Trinidad. Neither Amshoff nor Urban seems to have suggested a relationship between M . platyclada and A. edulis; Urban indeed applied the latter name to quite another species (see M . edulis var dominicana). The type of A. edulis is in fruit, and consequently much of the characteristic pubescence has been eroded from the panicles and the calyx-lobes, but the leaf-shape, the flattened panicle-branches and the many remaining dibrachiate hairs indicate clearly its identity with M . platyclada.

Steyermark's collections (nos. 86460, 88430) from near Hato de Nuria, Bohvar, Venezuela, represent a nearly glabrous form with mostly obovate leaves, essentially indistinguishable from specimens of M . platyclada from Trinidad and Tobago, e.g., Broadway 4461. A densely rusty-pubescent form with acuminate, ehiptic-oblong leaves, Steyermark & Aristeguieta 44, also from the Bolivar lowlands, lacks flowers. A plant from Serrania Paru, Amazonas, from an elevation of 180o' m. Cowan & Wurdack 31122, is similar to the last but less strongly pubescent. Only one of the above (Steyermark 86460) is in flower; in this specimen the calyx-lobes are partly deciduous, but the hypanthium is not spht (or somewhat so in heavily pressed flowers). Until more material can be studied, these plants from slightly differing populations are assigned to Myrcia platyclada with some reservations. The plant from the Kaieteur Savannah, British Guiana, described by Amshoff as Aulomyrcia platyclada var kaieleurensis, resembles the type of Myrcia platyclada in having obtuse, obovate leaves and somewhat flattened rachises; the leaves are rigid, and the plant is glabrous or essentially so. The following specimen, with half-grown fruit only, seems to represent the same taxon. V E N E Z U E L A . Bolivar: Chimanta Massif, Torono-tepui, elev 500-515 m, 9 Mar 1955, Steyermark & Wurdack 1317 (MICH).

Distribution:French Guiana South America|