1961] 



BOTANY OF THE GTJAYANA HIGHLANDS PART IV (2) 



7 



are polyphyletic, and that the Dilleniaceae, the Violaceae, the Eucryphiaceae, 

 and the Hypericaceae are possibly all involved in the phyletic history. A key 

 to the genera of the Luxemburgieae, upon which we have drawn, is likewise 

 presented in the thesis. 



Of the sixteen genera of the Luxemburgieae here recognized, six {Tyleria, 

 Poecilandra, Leitgebia, Philacra, Adenanthe, and Adenarake) are wholly en- 

 demic to the upland habitats of the Guayana sandstone mountains. The genus 

 Sauvagesia is well represented in the Guayana Highland, and possibly finds its 

 most primitive species here ; indeed, this area may well be the center of distribu- 

 tion of this the largest and most widespread genus of the tribe. The monotypic 

 Pentaspatella, certainly closely related to Sauvagesia (and included in Leitgebia 

 by Dwyer), is found in low-altitude savannas in the Orinoco-Negro drainage, 

 in which the floras are conspicuously related to those of the sandstone high- 

 lands. Blast emanthns and Wallacea, perhaps most closely to be associated with 

 the Highland Poecilandra, are confined to the Rio Negro-Alto Orinoco drain- 

 ages. Ten of the sixteen genera are thus found exclusively within Guayana. 



Lavradia, with Adenarake of the Guayana Highland its most immediate 

 congener, is found exclusively in the Brazilian Highland to the south of the 

 Amazon, as is the larger genus Luxemburgia, which finds its closest relative in 

 the Guayana genus Philacra. 



The remaining genera, Cespedezia, with four or five widespread Hylean 

 species, Rhytidanthera with four Andean species, Godoya with two Andean 

 species, and Krukoviella with a single species known from the upper Amazon, 

 occupy a third geographic genus-grouping within the tribe. 



Key to the Tribes and Genera of American Ochnaceae 



1. Carpels free and distinct; receptacle conspicuously enlarged at maturity; Ourateeae 



(three genera; only 1 American, + 100 spp.). 1. Ouratea. 



1. Carpels fused; receptacle not enlarged at maturity. 

 2. Fruit an indehiseent nut; seed without endosperm; Elvasieae (a single American 



genus, 5-6 spp.). 2. Elvasia. 



2. Fruit drupaceous or capsular; seed with endosperm; ovary 2-5-celled; Luxem- 

 burgieae (15 genera, all American except Fleurydora of Africa). 

 3. Stamens completely cyclic, i.e. forming a complete ring around the base of the 

 ovary. 



4. Pistils tricarpellate or pentacarpellate ; capsules intruded at the sutures ; ovules 

 borne on intruded parietal placentae. 

 5. Pistils pentacarpellate, the styles short, no more than one-sixth the length 

 of the ovary; staminodia lacking; bracts appendaged proximally and 

 ventrally. 



6. Stipules of uppermost leaves persistent; sepals less than half the length 

 of the petals in the mature bud; stamens numerous; seed linear-fusi- 

 form. (7 spp. acc. Dwyer). 3. Cespedezia. 

 6. Stipules all deciduous; sepals half the length of or equal in length to the 

 petals in the mature bud. 

 7. Leaves compound; stamens 50-70, the filaments at least half the length 



of the anthers. (4 spp.) 4. Rhytidanthera. 



7. Leaves simple; stamens 10, the filaments less than half the length of 

 the anthers. 



8. Sepals obviously unequal, appendaged ventrally and proximally; 



anthers dehiscing by two pores. (2 spp.) 5. Godoya. 



8. Sepals subequal, not appendaged ventrally or proximally; anthers 



dehiscing by a single pore. (1 sp.) 6. Krukoviella. 



5.. Pistils tricarpellate, the styles subulate, as long as or longer than the 

 ovary; staminodia rarely lacking; bracts appendaged neither ventrally 

 nor proximally. 



