ULMACEM. 157 



gynaecium, the ovary of which, surmounted by a style with two 

 long stigmatiferous subulate branches, encloses a descending ovule 

 and is surrounded by a gamosepalous calyx. Around and below 

 this are the imbricate bracts of the involucre. Olmcdia consists of 

 trees of tropical South America. Beside it is ranged Antiaris (fig. 

 119-121) inhabiting the warmest regions of Asia and Oceania, which 

 differs only in its ovary being inferior instead of superior, and in the 

 parts of its female calyx being independent instead of being 

 united to a variable extent below. The flowers are monoecious. 

 Pseudolmedia, growing in the same countries as Olmcdia, has the 

 inferior ovary of Antiaris, with a descending or laterally attached 

 ovule, and a lateral style emerging from an apical orifice in the 

 floral envelope. The male flowers are destitute of perianth aud re- 

 presented by a variable number of stamens inserted within the 

 imbricate bracts of the involucre. 



In most genera of Olmcdieœ, the female flowers are numerous 

 upon each capitule on which they are arranged in glomerules. In 

 that only is Castilloa (fig. 122), a caoutchouc tree of central 

 America, distinguished from Pseudolmedia. It has otherwise the 

 aperianthous male flowers, the inferior ovary and the style with two 

 stigmatiferous divisions of Pseudolmedia. Helicostylis, a genus from 

 northern Brazil and Guyana, has the inflorescence and female 

 flowers of Castilloa, but tetrandrous male flowers and a palyx of 

 four sepals like Antiaris. This genus derives its name from the 

 stylary branches being much spirally twisted ; a tendency existing 

 but in a much less degree in Castilloa. Not only is the ovary 

 inferior relatively to the perianth in the two preceding genera, but 

 it is also adherent on one side to the cavities from which the 

 receptacle of the inflorescence grows, like that of Artocarpus. The 

 same is the case in Noycra, a tree of Guyana, the male flower of 

 which is unknown, and the style proceeds- from a simple apical 

 opening in the epigynous perianth, as in Pseudolmedia. In Naucle- 

 opsis, on the contrary, the inferior ovary is entirely buried in the 

 receptacular tissue itself, to which it adheres in every part. It is a 

 tree of northern Brazil. Maquira and Perebea, which belong to 

 Guyana and Columbia, and have tetramerous and perianthous male 

 flowers, differ from all the preceding genera in that their female 

 flowers are simply placed upon the surface of the common receptacle, 



