EXOGENOUS OK DICOTYLEDONOUS PLANTS. 



419 



819. Ord. RllizoplloraceaB {Mangrove Family) consists of a few- 

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

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

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

 calyx, tw^o-celled, wdth two pendulous ovules in each cell. These 

 plants are remarkable for their opposite leaves, Avitli interpetiolar 

 stipules, and for the germination of the embrj-o Avhile within the 

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

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



820. Ord. CombretaceiE 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. Ord. OnagraceOE {Evening-Primrose Famthj). 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 jiroduced beyond it into a tube. 



FIG 822. Flower of (Enothera fruticosa. 823. The same, with the petals 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 Ilalorageaa). 827. Magnified flower, with the sub- 

 tending leaf. 828. Vertical section of the ovary. 829. Vertical section of the fruit and seed. 



