OKDEXS OF ANGIOSPERMS, 493 



saline ponds in Nebraska, and R. maritima along the seacoast 

 and in saline districts in the interior. 



The water-plantain family (Alismaceae) includes the water- 

 plantain (Alisma) and the arrow-leaves (Sagittaria). 



The tape-grass family (Vallisneriaceae) includes the tape-grass, 

 or eel-grass (the curious Vallisneria spiralis). 



943. Order Graminales. Two families. 



The grass family (Gramineae), the grasses and grains. 

 The sedge family (Cyperaceae), the sedges. 



944. Order Palmales, with one family, Palmaceae, includes 

 the palms, abundant in the tropics and extending into Florida. 

 Cultivated in greenhouses. 



945. Order Arales. 



The arum family (Araceae). Flowers in a fleshy spadix. Ex- 

 amples: Indian turnip (Arisaema), sweet-flag (Acorus), skunk- 

 cabbage (Spathyema). 



The duckweed family (Lemnaceae). (Examples: Lemna, 

 Spirodela, Wolffia. See paragraphs 51-53.) 



946. Order Xyridales, from the genus Xyris, the yellow- 

 eyed grass family (Xyridaceae). Species mostly tropical, but 

 a few in North America. Other examples are the pipewort 

 family (Eriocaulaceae, example, Eriocaulon septangulare) , the 

 pineapple family (Bromeliaceae, example, the pineapple culti- 

 vated in Florida) ; the Florida moss or hanging moss (Tillandsia 

 usneoides); the spiderwort family (Commelinaceae), including 

 the spiderwort (Tradescantia, several species in North America) ; 

 the pickerel- weed family (Pontederiaceae), including the genus 

 Pontederia in borders of ponds and streams. 



947. Order Liliales. Some of the families are as fol- 

 lows : 



The rush family (Juncaceae, example, Juncus), with many 

 species, plants of usually swamp habit. 



The lily family (Liliaceae, examples: Lilium, Allium = Onion, 

 Erythronium, Yucca). 



The iris family (Iridaceae, examples: Iris, the blue-flag, 

 fleur-de-lis, etc.). 



