Fig. 117.—Isocarpous sympetalæ (Primulinæ, Diospyrinæ). A, shooting-star, Dodecatheon (Primulaceæ), × ½. B, section of a flower, × 1. C, diagram of the flower. D, Moneywort, Lysimachia (Primulaceæ), × ½. E, a perfect flower of the persimmon, Diospyros (Ebenaceæ), × 1. F, the same, laid open: section of the young fruit, × 2. H, longitudinal section of a ripe seed, × 1. em. the embryo. I, fruit, × ½.
The sea-rosemary (Statice) and one or two cultivated species of plumbago are the only members of the plumbago family (Plumbagineæ) likely to be met with. The remaining families of the Primulinæ are not represented by any common plants.
The third and last order of the Isocarpous sympetalæ has but a single common representative in the United States; viz., the persimmon (Diospyros) ([Fig. 117], E). This belongs to the family Ebenaceæ, to which also belongs the ebony a member of the same genus as the persimmon, and found in Africa and Asia.
The second division of the Sympetalæ (the Anisocarpæ) has usually but two or three carpels, never as many as the petals. The stamens are also never more than five, and very often one or more are abortive.
Fig. 118.—Types of Anisocarpous sympetalæ (Tubifloræ). A, flower and leaves of wild phlox (Polemoniaceæ), × ½. B, section of a flower, × 1. C, fruit, × 1. D, flower of blue valerian (Polemonium), × 1. E, flowers and leaf of water-leaf, Hydrophyllum (Hydrophyllaceæ), × ½. F, section of a flower, × 1. G, flower of wild morning-glory, Convolvulus (Convolvulaceæ), × ½. One of the bracts surrounding the calyx and part of the corolla are cut away. H, diagram of the flower. I, the fruit of a garden morning-glory, from which the outer wall has fallen, leaving only the inner membranous partitions, × 1. J, a seed, × 1. K, cross-section of a nearly ripe seed, showing the crumpled embryo, × 2. L, an embryo removed from a nearly ripe seed, and spread out; one of the cotyledons has been partially removed, × 1.
The first order (Tubifloræ) has, as the name indicates, tubular flowers which show usually perfect, radial symmetry (Actinomorphism). There are five families, all represented by familiar plants. The first (Convolvulaceæ) has as its type the morning-glory (Convolvulus) ([Fig. 118], G), and the nearly related Ipomœas of the gardens. The curious dodder (Cuscuta), whose leafless, yellow stems are sometimes very conspicuous, twining over various plants, is a member of this family which has lost its chlorophyll through parasitic habits. The sweet potato (Batatas) is also a member of the morning-glory family. The numerous species, wild and cultivated, of phlox ([Fig. 118], A), and the blue valerian (Polemonium) ([Fig. 118], D), are examples of the family Polemoniaceæ.
