EXOGENOUS Oil DICOTYLEDONOUS PLANTS. 



419 



819. Orel. Rllizoplioracca; {Mangrove Family) consists of a few 

 tropical trees (extending into Florida and Louisiana), growing in 

 maritime swamps, where they root in the mud, and form thickets 

 on the verge of the ocean. The ovary is often partly free from the 

 calyx, two-celled, with two pendulous ovules in each cell. Tiiese 

 plants are remarkahle for their opposite leaves, with interpetiolar 

 stipules, and for the germination of the embryo while within the 

 pericarp. — Ex. Rhizophora, the Mangrove (Fig. 141). The as- 

 tringent bark has been used as a febrifuge, and for tanning. 



820. Ortl. CombrelaceiE consists of tropical trees or shrubs (which 

 have one or two representatives in Southern Florida), often apeta- 

 lous, but with slender colored stamens ; distinguishable from any of 

 the preceding orders of this group by their one-celled ovary, with 

 several suspended ovules, but only a solitary seed, and convolute 

 cotyledons. — Ex. Combretum. 



821. Grd. OnagracCCB {Evening-Primrose Family). Herbs, or rare- 

 ly shrubby plants, with alternate or opposite leaves, not dotted nor 



furnished with stipules. Flowers usually tetramerous. Calyx ad- 

 herent to the ovary, and usually produced beyond it into a tube. 



TIG 822. Flower of Oenothera fruticosa 823. The same, with the petnls removed. 824. 

 Magnified grains of pollen, with some of the intermixed cellular threads. 825. Cross-section 

 of the four-lobed and four-celled capsule. 



FIG 826. Ilippuris vulgaris (suborder Halorageic). 82" Magnified flower, with the sub- 

 tending leaf. S28. Vertical section of the ovary 8-X Vortical section of the lruit aud seed 



