[Vol. 2 



122 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



Family 15. Commelinaceae. Spiderworts. Succulent herbs 

 with 3 or 2-celled pistil ; stamens 6 ; perianth of two dissimilar 

 whorls of three similar leaves. Commelina, Tradescantia. 

 (Pf. 2 4 :60.) 



Family 16. Xyridaceae. Rush-like plants with a 1-celled 



incompletely 3-celled pistil; stamens 3; perianth of two 

 dissimilar whorls, each of three similar leaves. Xyris. (Pf. 



2*: 18.) 



Family 17. Mayacaceae. Slender, creeping, moss-like plants 

 with 1-celled pistil; stamens 3; perianth of two dissimilar 

 whorls, each of three similar leaves. Mayaca. (Pf. 2 4 : 16.) 



Family 18. Juncaceae. Rushes. Herbs with narrow 

 leaves; pistil 1-3-celled; ovules solitary or many; fruit a dry 

 3-valved pod. J uncus, Luzula. (Pf. 2 5 :1.) 



Family 19. Eriocaulonaceae. Rush-like herbs with flowers 

 in close heads ; perianth segments 6 or less, small ; pistil 3 or 

 2-celled; ovules orthotropous, pendulous. Eriocaulon. (Pf. 

 2 4 :21.) 



Family 20. Thurniaceae. South American herbs, with 



small, 1-nerved leaves, and small axillary flowers. Thurnia. 

 (Syllabus, 139.) 



Family 21. Rapateaceae. Tall, sedge-like marsh herbs 

 with 3-celled pistil ; stamens 6, in pairs ; perianth of two dis- 

 similar whorls, each of three similar leaves. Rapatea. (Pf. 



2 4 :28.) 



Family 22. Naiadaceae. Slender, branching, wholly sub- 

 merged aquatics, with sheathing, mostly opposite leaves, and 

 monoecious or dioecious flowers. Naias. (Pf. 2 1 : 214.) 



Order Arales. Compound pistil, mostly tricarpellary, su- 

 perior; ovules one or more; perianth reduced to scales or 

 entirely wanting ; endosperm usually present. ( Species about 

 1052.) 



Family 23. Cyclanthaceae. Mostly herbaceous plants with 

 broad, petioled leaves having parallel venation ; pistil 1-celled ; 

 ovules many, on four parietal placentae. Cyclanthus. (Pf. 



2 3 :93.) 



