462 



EXOGENOUS OR DICOTYLEDONOUS PLANTS. 



861. Ord, Amarantaceae (the Amaranth Family}. Herbs, with 

 opposite or alternate leaves ; the flowers in heads, spikes, or dense 

 clusters, imbricated with dry and scarious bracts which are usually 

 colored. Calyx of three to five sepals, which are dry and scari- 

 ous, like the bracts. Stamens five or more, hypogynous, distinct 

 or monadelphous : anthers frequently one-celled. Embryo annu- 

 lar, always vertical. Otherwise nearly as in Chenopodiacese. 

 Ex. Arnarantus, Gomphrena, &c. Weeds. A few Amaranths 

 are cultivated for their dry and enduring richly-colored flowers. 



862. Ord, Nyctaginaceae, Herbs or shrubs, with opposite leaves ; 

 distinguished by their tubular and infundibuliform calyx, the upper 

 part of which resembles a corolla, and at length separates from 

 the base, which hardens and incloses the one-celled achenium-like 

 fruit, appearing like a part of it. Stamens hypogynous, 1-20. 

 Embryo coiled around the outside of mealy albumen, Flowers 

 involucrate, often showy. Mirabilis (Four-o'clock) has a one- 

 flowered involucre exactly like a calyx, while the latter resem- 

 bles the corolla of a Morning-Glory. Plants of warm latitudes j 

 many on our Southwestern frontiers. 



863. Ord, PolygonaceflB (the Buckwheat Family). Herbs with al- 



FIG. 984. Polygonum Pennsylvanicum. 985. Flower laid open. 986. Section of the ovary, 

 showing the erect ovule. 987. Section of the seed, showing the embryo, at one side of albumen. 



