

[Vol. 2 



126 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



celled; ovules 1 in each cell. Calathea, Maranta. (Pf. 2° : 33.) 



Order Orchidales. Compound tricarpellary pistil inferior ; 

 flower-leaves in each whorl mostly unlike in shape (Jlower 

 irregular, zygomorphic) ; seeds numerous, minute, without 

 endosperm. (Species about 7578.) 



Family 44. Burmanniaceae. Flowers irregular; stamens 

 3 or 6. Burmannia. (Pf. 2 6 :44.) 



Family 45. Orchidaceae. Orchids. Flowers irregular; 

 stamens 1 or 2. Cypripedium, Orchis, Platanthera, Vanilla, 

 Spiranthes, Epidendrum, Dendrobium, Oncidium. (Species 



7521.) (Pf.2«:52.) 



In the Orchidales, and especially in the Orchidaceae, we have 

 what is generally regarded as the highest development of 

 monocotyledonous plants, and yet it must be acknowledged 

 that many of their most striking flower structures are rather 

 easily made entomophilous modifications of the perianth, the 

 most mobile portion of the plant. In many ways the ' ' grassy" 

 plants (especially the Poaceae) show greater and more pro- 

 found structural modifications than do the much more con- 

 spicuous orchids. With the orchids the epigynous monocoty- 

 ledonous phylum ends. 



Class 33. OPPOSITIFOLIAE (DICOTYLEDONEAE). 



The Dicotyledons. Leaves of young sporophyte opposite; 

 leaves of mature sporophyte opposite or alternate, usually 

 reticulate-veined; fibrovascular bundles of the stem in one or 

 more cylindrical layers. (Species about 108,800.) 



As indicated above the dicotyledons are here considered to 

 have had their beginning earlier than the monocotyledons, 

 which must be regarded as having diverged very early from 

 the primitive dicotyledons, and developed into a relatively 

 small lateral branch. The point of divergence of the mono- 

 cotyledons from the dicotyledons must have been in the order 

 Ranales, probably in the neighborhood of the Ranunculaceae . 

 It is not probable that the early (woody) magnoliads or ano- 

 nads gave rise to the monocotyledonous divergence ; it is much 

 more probable that this modification arose after the reduction 

 had taken place from the ligneous to the herbaceous Ranales. 



