224 FAMILIES OF FLOWERING PLANTS 
Cuarrer XXXI.—Order Polemoniales or Tubiflorae. 
This order consists mainly of herbs. It embraces twenty families, 
of which the most important are the Convolvulaceae, Polemoniaceae, 
Hydrophyllaceae, Boraginaceae, Verbenaceae, Labiatae, Solanaceae, 
Scrophulariaceae, Bignoniaceae and Acanthaceae. The corolla is gam- 
opetalous throughout, with the stamens more or less united with its 
tube. The ovary is superior and compound. 
Family Convolvulaceae. Morning-glory Family. Contains about 40 
genera and nearly 1,000 species, of wide distribution. They are herbs 
or vines, rarely shrubs or trees, with alternate leaves and axillary 
flowers. The calyx is usually persistent, the 5-angled or 5-lobed corolla 
convolute (twisted) in the bud. Stamens, 5; ovary, 2-3-celled, becoming 
a 2-4-valved capsule. 
The two most important genera, Convolvulus and Ipomoea are highly 
esteemed as furnishing many ornamental vines. In fact, there is prob- 
ably no genus in which the species are more uniformly handsome- 
flowered throughout than the Ipomoea, to which the common morning- 
glory belongs. (Fig. 194). The leaves are of every conceivable shape and 
degree of lobation, while the flowers exhibit a great variety of colors, par- 
ticularly in the tropics. The beautiful white moonflower, formerly in- 
cluded in Ipomoea, is now usually placed in a distinct genus (Calonyction). 
The Convolvulaceae are of very slight economic importance; the gum-resin 
known as scammony, is produced by Convolvulus Scammonia, while the 
purgative drug jalap is yielded by a species of Jpomoea. 
Family Cuscutaceae. Dodder Family. These are leafiess parasitic 
twining vines, all comprised in the single genus Cuscuta, of which there 
are about 100 species, of wide distribution. The calyx and corolla are 
5-lobed or 5-parted, the coralla-lobes frequently bearing scales alternate 
with them. The stamens are 5; ovary 2-celled, becoming a 1-4-seeded 
capsule. 
The seeds of the dodder germinate in the ground like those of ordi- 
nary plants, and the young seedling soon attaches itself by means of 
numerous minute suckers to the adjacent herbage. When, it has ob- 
tained a sufficient hold to enable it to secure the required amount of 
nutrition its root and lower portion perish. When fully grown it 
resembles a mass of white or orange-colored tangled threads spread 
over the foliage of the herbs on which it is found. While some species, 
like C. Gronovii, are quite cosmopolitan in their tastes, occurring on a 
variety of plants, others, like C. Trifolii, are confined strictly to one 
kind of plant. 
Family Polemoniaceae. Polemonium Family. This group, con- 
sisting entirely of herbs, includes about 10 genera and 200 species, by 
