14 NATURAL HISTORY OF PLANTS. 
smaller number in Asia and Madagascar. The genera ddronia, 
Okenia, Nyctaginia, Pentacrophys, Selinocarpus reduced to one, or a 
small number of species, only inhabit the south-western regions of 
North America. Bo/doa and Colignonia extend farther south, in the 
west of South America. d//ionia occupies a long western zone from 
Mexico to Chili. Oxybaphus is wholly American, except one Indian 
species, which occupies the sides of the Himalayas. J/iradbilis is 
solely American ; but J/. Jalapa has been introduced into all the 
warm and temperate countries of the globe.’ 
The Nyctaginacee have been considered as allied at the same time 
to the Polygonacea, Chenopodiaceae, Plumbaginacee, Phytolaccacee, 
Cannabinacee, Valerianaceæ, Piperacee. Despite of external 
resemblances, they are sharply distinguished from the first three 
families, for in these the basilar placenta bears the ovule, around 
which the wall of the ovary is formed by the union of two or several 
carpellary leaves. The Cannabinacee have also more than one 
carpellary leaf to the gynæceum and an axile placenta supporting a 
single descending ovule in the fertile cell. The Valerianacee have 
none of the essential characters of the Nyctaginacee ; for their ovary 
is really inferior, the insertion of their perianth being what is called 
epigynous.” The ovary of the Wycfaginacee on the contrary is quite 
free and superior; but it is constructed absolutely like that of 
Piperacee and Urticacee, that is to say, formed of one single 
carpellary leaf inserted on the side of the axis which bears one single 
ascending ovule. However, the ovule of the Nyctaginacee, always 
reflexed and not orthotropous, distinguishes them clearly from the 
Piperacee, which have neither their petaloid perianth nor their 
embryo external to the albumen, but possess a double albumen. 
The gynæceum of Myclaginacea is however also constructed like 
that of the unicarpellary Phytolaccacee, that is to say, the vince. 
These last have also a farinaceous albumen enveloped by the 
embryo; and they are only distinguished by the organization of 
their perianth, which has no inferior persistent thickened part, to 

1S. Warson, in Unit. St. Geogr. Expl. of  perianth, and its superior part to a corolla, is 
fourt. par., Bot., 286, Hermidiwn, n. 8, t. 82. quite inadmissible. The affinity appealed to in 
Flowers in capituliform racemes, with 5-7 Pisonia and Viburnum is only due to superficial 
stamens, analogous to those of Mirabilis. appearances. ‘lhe unicarpellary Tymelaceæ are 
? The idea which A. L. DE Jussieu had of only distinguished from the Nyctaginacee in the 
comparing a calyx to the persistent part of the flower by the direction of the ovule. 
