SUPPLEMENT. 
THE FAMILIES OF FLOWERING PLANTS. 
By Cuaries Louis Potiarp. 
° CHAPTER VIII. ( Continued.) 
Family Commelinaceae. Spiderwort Family. This group is al- 
most wholly of tropical distribution; it contains 25 genera and about 
350 species, Commelina and Tradescantia 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 family they have a conspicuous perianth consisting of both 
calyx and corolla. The stamens are often wooly with handsomely 
colored hairs, while the prevailing hue of the corolla is purple or blue. 
In Commelina 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- 
niemorate 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 differen- 
tiated into calyx and corolla. The Water Hyacinth (Piaropus crassi- 
pes) an ornamental exotic which had proven a troublesome weed in 
some rivers of Florida, is also a mem ber of this family.* 
*See the article by Mr. A. H. Curtiss on the Mates Hyacinth in a recent issue 
of Toe Piant Wor.p. 
