24 



MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



(vol. 10 



RUTACEAE' 



,8 



In the following' account several taxa are described as new, but I have also 

 included descriptions of older taxa which were not fully characterized originally 

 or which are much better known now as a result of numerous recent collections. 

 In citing' the place of deposit of these collections, the reference to the New York 

 Botanical Garden sheet of the Maguire et al. collections has been omitted, since 

 it is certain that the first set of these will be found in the New York herbarium. 



Raveniopsis Gleason, Brittonia 3:166. Oct 1939. 



Shrubs or small trees, mostly with simple leaves. Inflorescence a simple 

 raceme, or dischasial with two cincinnoid racemes and a terminal flower at the 

 apex of the peduncle, or rarely the flower solitary; flowers pentamerous, the 

 calyx, corolla, and androecium variously zygomorphic. Sepals free or very 

 shortly united basally, usually obviously foliaceous, generally considerably 

 longer than wide, imbricate. Corolla tube cylindric, arcuate, flaring toward the 

 apex in a spreading limb, the petals unequal. Fertile stamens two, the ligulate 

 filaments more or less joined with those of the three or more staminodia in a 

 filament tube, adherent to the corolla tube at the base or much higher, the 

 anthers with saccate to flabellate appendages at their base. Disk cupular, usually 

 completely enclosing the ovary, truncate to somewhat lobate. Stigma obliquely 

 5-lobed. the style slender, the ovary 5-carpellate, the carpels free except in the 

 styles; ovules 2 in each carpel. Fruit of 1-5 cocci, each one-seeded, dehiscing 

 longitudinally, the exocarp separating from the whitish endocarp. 



Type species : Raveniopsis tomentosa Gleason, op. cit. 167. 



As Gleason indicated in his original publication of this genus, several differ- 

 ences separate it from the allied genus, Ravenia. Before the present publication, 

 Ravenia has been considered to occur both in the lowlands and on the summits 

 of the table-mountains of Guayana, but tin 1 species of the latter region are herein 

 transferred to Raveniopsis. 



The principal, technical characteristic that separates the two genera, as 

 interpreted here, is the presence of basal appendages on the tw 7 o fertile anthers 

 of Raveniopsis; but there are at least two other tendencies: (1) in Ravenia the 

 flowers are solitary or borne in few-flowered, subumbellate clusters or racemes, 

 but in the allied genus the flowers are usually rather closely arranged in simple 

 or dichotomous racemes or spikes; (2) in Ravenia the sepals are about as long 

 as wide and not obviously foliose, in Ra/veniopsis the sepals are usually longer 

 than wide and obviously foliose. 



The species of Raveniopsis are found thus far exclusively on the summits of 

 the tepuis in the Guayana Highland between 1000 and 2500 meters elevation; 

 the greater number of species occurs at about the 2000-meter level. Thus an 

 altitudinal disjunction is correlated with the morphological distinctions and sup- 

 ports the realignment of species presented here. 



-■ [nflorescence :i simple raceme; larger sepals narrowly lanceolate, about 1.5 mm 



Key to the Species of Raveniopsis 



1. Leaves trifoliolate, chartaeeous to thinly coriaceous, never rigid. 

 1. Leaves unifoliolate or simple, rigid. 



2. 

 3. 



wide. Pubescence simple. 



1. R. trifoliolata. 



8 By Richard S. Cowan. 



