542 POLEMONIACE^ — HYDEOPHYLLACE^ — CONVOLVULACE^. 



ascending, in a single or a double row ; embryo straight, in the axis of 

 a fleshy or horny albumen ; cotyledons foliaceous, elliptical or cordate ; 

 radicle inferior, next the hilum. — Herbaceous or climbing plants, with 

 opposite or alternate, simple or compound leaves. They inhabit tem- 

 perate countries chiefly, and they abound iu the north-western part of 

 America. There are 17 genera enumerated by Lindley, .including 

 116 species. Examples — Polemonium, Phlox, Cobsea (fig. 350, p. 

 220), CoUomia, Gillia, Leptosiphon, Oantua. 



Many of the plants of this order have showy flowers, and are 

 commonly cultivated in flower-borders. Connected with the episperm 

 of various species of CoUomia are numerous spiral cells, and when the 

 seeds are moistened with water, the mucus surrounding the cells is 

 dissolved, so that the spiral fibres are uncoiled. The movements of 

 these fibres, when uncoiling, are beautifully seen under the microscope. 

 The fibres carry with them a mucous envelope which has the appear- 

 ance of a membrane. Polemonivm, cceruleum, Greek Valerian, or Jacob's 

 ladder, is bitter. In Siberia poultices are prepared from its leaves. 

 The Russians fancy that a decoction of it is useful in hydrophobia. 



Order 123. — Hydeophyllace^, the Hydrophyllum Family. 

 (Monepet. Hypog.) Calyx 5-parted, persistent. CoroUa monopetalous, 

 hypogynous, regular, 5-cleft ; aestivation plicate or imbricate. Sta^ 

 mens 5, inserted upon the corolla, and alternate with its segments ; 

 filaments sometimes petaloid ; anthers deeply-lobed at the base, often 

 versatile, 2-celled, dehiscing longitudinally or transversely. Disk 

 annular or 0. Ovary free, 1-2-3-celled j ovules definite or indefinite; 

 style 1 or 2 j stigmas usually 2. Fruit capsular, 2-valved, 1-2-ceUed, 

 with a parietal or a large central placenta. Seeds with a brittle or 

 reticulated testa ; embryo in the midst of fleshy or cartOaginous albu- 

 men ; radicle next the hUum. — Trees, shrubs, or herbs, with opposite, 

 or alternate, exstipulate, often lobed leaves. They occur both ia the 

 northern and southern parts of America chiefly. They have no pro- 

 perties of importance. Many have showy flowers, and some have 

 glandular or stinging hairs. The order has been divided into two 

 tribes : — 1. HydrophyUese, including Hydrolese of authors, with the 

 anthers dehiscing longitudinally, disk present, ovary 1-2-celled, styles 

 2. 2. Diapensiese, with anthers dehiscing transversely, disk 0, ovary 

 3-ceUed, style single. There are 20 known genera and 81 species. 

 Examples — Hydrophyllum, Hydrolea, Nemophila, Eutoca, Phacelia, 

 Diapensia. 



Order 124. — Convolvulaoe*, the Convolvulus or Biadweed 

 Family. (Monopet^ Hypog) Calyx in five divisions, persistent, im- 

 bricated, often bracteated (figs. 762-764). Corolla monopetalous, 

 hypogynous, deciduous, regular ; limb 5-lobed, with a plaited or con- 

 torted aestivation (fig. 763 2)) ; tube sometimes with scales, alternate 

 with the lobes of the limb. Stamens 5, inserted in the base of the 



