SUPPLEMENT. 



THE FAMILIES OF FLOWERING PLANTS. 



By Charles Louts Pollard. 

 CHAPTER VIII. {Continued.) 



Family Commelinaceae. Spiderwort Family. This group is al- 

 most wholly of tropical distribution; it contains 25 genera and about 

 350 species, Conimelina and Tradescantla being the only two genera 

 that reach the United States. The plants are herbs, frequently with 

 long linear leaves, and with clustered flowers that open only in the 

 sunshine and quickly wither when gathered. The flowers are sub- 

 tended by leafy spathes, thus showing relationship to the Aroids; but 

 unlike that famil}^ they have a conspicuous perianth consisting of both 

 caij'x and corolla. The stamens are often wooly with handsomely 

 colored hairs, while the prevailing hue of the corolla is purple or blue. 

 In Commellna one of the three petals is much smaller than the other 

 two, and it is said that the author of the genus intended thus to com- 

 memorate the three brothers Commelin, two of whom were botanists, 

 while the third had no interest in the science. 



Family Pontederiaceae. Pickerel-weed Family. Every fisher- 

 man knows the pickerel-weed {Pontederia), which, with its wand- like 

 spikes of blue flowers and handsome emersed cordate leaves, affords 

 shelter for many a fine fish. The family is not a large one, containing 

 only 5 genera and about 25 species, natives of America, Asia and 

 Africa. In general the plants may be known by their flowers, which 

 have a six-parted perianth, all its divisions being alike and not difleren- 

 tiated into calyx and corolla. The Water Hyacinth [Piaropvs crassi- 

 Xx's) an ornamental exotic which had proven a troublesome weed in 

 some rivers of Florida, is also a member of this family.* 



*See the article by Mr. A. H. Curtiss on the Water Hyacinth in a recent issue 

 of The Pi,axt World! 



