20 ON SOUTH-AMERICAN APOCYNACE^. 



Thevetia. 



A new species, from Venezuela, is here added to this genus, which nearly approaches 

 the handsome plant described and figured by Mr. Bentham in the Botany of the 

 ' Sulphur,' p. 124, tab. 43. I will first, however, explain my view of the carpological 

 structure of the genus, which is not quite exactly described by Prof. DeCandoUe m his 

 'Prodromus;' and it is difficult to understand the long description of Dr. Miiller m 

 Mart. ' PI. Bras.,' which is not correct. 



My analysis was made from a plant of T. ahouai, cultivated in Rio, de Janeiro. This 

 species is wdl figured in Lamarck's ' lUustr.' tab. 170 : the compressed globular ovary is 

 pseudo-i-locular, the true dissepiment being across the shorter diameter, having on each 

 side a very broad placentary expansion extending nearly to the wall of the cells m the 

 direction of the longer diameter, thus appearing pseudo-4-celled, a single ovule being 

 peltately attached upon each side of each branch of the placenta. This structure is 

 maiutained in the ripe fruit ; within the pericarp is a heart-shaped compressed osseous 

 nut, shown in a reversed position in Lamarck's plate : along the emarginated apex of this 

 nut is a suture, which extends nearly to the base along each edge, into which a knife 

 easily penetrates ; but it requires some force to cut through its more solid base : we thus 

 divide the nut into two plano-convex portions, the division being through the bUamellar 

 placentEe : upon the surfaces of the division, on each face a cord of spiral vessels rises 

 from the base, .diverges upwards, and is lost at a spot opposite to each seed, and therefore 

 opposite to the hilum of each : around this spot, within the cell, is a deep hollow in 

 the placenta, formed by the pressure of the rounded peltate hilum : the 4 seeds, which 

 fill the spaces of the 4 pseudo-cells, are irregularly globose, flattened on one side around 

 the large convex hilum : the testa is stoutly chartaceous, of a brownish colour, and so 

 firmly attached to the hilum, that it cannot be there detached without rupture ; this 

 integument is lined within by a network of snow-white branching threads of the raphe ; 

 the inner integument is free, membranaceous, and of a darkish colour, closely investing 

 an embryo, without any trace of albumen, which consists of 2 roundish plano-convex 

 fleshy cotyledons united by a short obtusely conical radicle, projecting horizontally and 

 centrifugally to the outer edge of the cell : this embryo is therefore heterotropous ; 

 i. e. the hUum is laterally placed between the two extremities of the embryo. The new 

 species before mentioned is defined in the following manner : — 



Thevetia calophylla, nob. : ramulis teretibus brunneo-opacis : foliis alternis, lanceolato-oblongis, imo 

 cuneatisj apice acute aciiminatis, chartaceis, marginibus subrevolutis, supra viridibus, opacis^ corru- 

 gulatis, ad nervos semiimmersos sulcatulis, subtus opacis, brunnescentibus, corrugulatis, nervis 

 omnino immersis; petiolo semitereti, limbo ll-12plo breviore : racemo brevi, terminali, paucifloro; 

 pedicellis subvalidis, calyce 3plo longioribus; sepalis oblongis, acutis, membranaceis, parallele 

 nervosis ; corollEe tubo cylindrico, supra medium ampliore, limbi segmentis 5, tubo dimidio brevi- 

 oribus, dolabriformibus, dextrorsum contortis, cum appendicibus 5 subacutis intra faucein altemis ; 

 stamiuibus 5, sub squamas insitis, inclusis, ex annulo pUoso ortis ; filamentis brevibus ; antheris 

 sine connectivo profunde 2-lobis, lobis imo divaricatis ; disco annulari, carnoso ; ovario paullo 

 longiore, glabro, 2-loculari ; stylo longo, filiformi, apice in clavunculam cylindricam 10-sulcatam imo 



