110 THE AMERICAN BOTANIST. 



from the screw-pines (Pandanus), a tropical genus, and 

 includes among our plants the cat-tails and burr-reeds. 

 The second order, the Naidales named for the genus NaiaSy 

 includes the pond-weeds, the eel-grass, the water plantains 

 and their relatives. The grasses and sedges constitute the 

 order Graminales, and the Arales named for the arum 

 family, contain in addition the duck-weeds (Lemna). This 

 completes the orders of apocarpous monocotyledons 

 represented in our territory. In the tropics another large 

 order, the Principes which contains the single famih' of 

 the palms {Palmacese), would be included. 



Of the sj-ncarpous inonocotyledons, the least special- 

 ized are the Xyridales named for the ^'cllow-ej^ed grasses 

 {Xyris). The\' include, also, the pipe-worts (Eriocaulon), 

 the pine-apples, the spider-worts (Tradescantia) , the pick- 

 erel-weeds and others. The next and most important 

 order, the Liliales, in addition to the great lil3' famih', 

 includes the rushes (Jiincus) and the smilax, amar3dlis,iris 

 and yam families. The order Scitaminales is mostly trop- 

 ical. To it belongs the arrow-root family {Marantaceee) 

 and various others, the most familiar representatives of 

 which are probabl3^ the cannas. The Orchidales, highest 

 in structure of the monocotyledons, complete the list of 

 orders. 



Glancing back we see a gradual line of development 

 beginning with humble marsh and water plants with 

 insignificant corolla and calyx and separate pistils, run- 

 ning through the lih^-worts with showy actinomorphic 

 flowers, often with the parts united, until it culminates in 

 the ZA'gomorphic orchids in which nearh' all parts of the 

 flower are united, the ovar3'- is inferior and the flowers 

 highh' specialized for cross-pollination. Here the line of 

 the monocot3dedons abruptl3^ ends. There is no imper- 

 ceptible gradation into the lowest of the dicot3dedons as 

 man3^ suppose. It therefore seems probable that the 

 monocot3dedons have had a separate line of development 

 with their highest t3'pes to be found among the orchids. 

 For comparison we shall next trace the line of evolution 

 in the dicotyledon. 



