20 FAMILIES OF FLOWERING PLANTS. 
flattened achene somewhat like that of a buttercup. The plantain-like 
leaves from which the popular name of the family is derived are most 
conspicuous in w{/ési«, which is a familiar bog plant throughout the 
continent. In this genus the flowers are small and inconspicuous, but 
in Sug/ttur/a they are often of some beauty, the inner perianth series, 
or corolla, consisting of three large white petals of the texture of 
crépe. Sagittur/u is called arrowhead from the shape of its leaves, 
which exhibit great diversity of form, but in many species are more 
or less like an arrow or spear head in outline. (See Fig. 15.) 
Family Butomaceae.— Water Poppy Family. Four genera, each 
monotypic, or consisting of a single species, and all exotics. The 
characters of the family, how- 
ever, are well illustrated in the 
beautiful yellow water poppy 
(ydroceys — nymphordes) 80 
often cultivated in ponds and 
tubs. The plants are herbs 
with extensively creeping root- 
stocks, or branching stems, and 
scapose flowers, solitary in the 
water poppy and umbelled in 
the other genera; the flowers 
are perfect, with a perianth 
composed of calyx and corolla, 
the latter often conspicuous. 
The fruit resembles that of the 
arrowhead or water plantain, 
but the*ovary contains more 
numerous ovules. 
I'am. 16.—Tape grass or wild celery, ( Vallixneria om - 
spiralis) showing enlarged staminate and pistillate Fami I y Vallisner laceae 
flowers, also the fruit, (After Britton and Brown, (H ydocharid aceae).—Tape- 
Ill. Fl. North. U.S ) : . 
grass or Frog’s-bit Family. 
Fourteen genera and £0 species 
of wide distribution, chiefly tropical. The only genera occurring in 
American are Vallisneria, Philotria and Malophila. The family is 
distinguished mainly by the divecious flowers, produced from the axils 
of enveloping bracts known as spathes; there is a small perianth com- 
posed of three to six segments. It is an interesting fact that V7///s- 
nerid, the true eel-grass or ‘‘wild celery’’, whose long ribbon-like 
