276 



M0N0PETAL0U8 ORDERS. 



or shrichs, often with milky juice. Leaves alternate. Calyx 

 persistent, in 5 divisions, much imbricated. Corolla regular, 

 deciduous ; the U?nb 5-lobed, plaited. Stamens 5, inserted into 

 the tube of the corolla, and alternate with its segments. Ova/ry 

 free, 2-4-celled ; styles united, or more or less distinct. Fruit 

 t-ucculeut or capsular. 

 Seeds with a small quan- 

 tity of mucilaginous albu- 

 men ; emhryo curved ; co- 

 tyledons foliaceous. 



a. Properties: the roots con- 

 tain an acrid milky jnice, which 

 is strongly purj^utive ; the C. ba- 

 tatas, or sweet potato, is an im- 

 portant article of food. 



Genera. — Evolvulus, Ipomoea 

 Convolvulus. 



Fig. 199, a, Ipoale batatoides ; 

 h, the pistil and annular disk ; 

 c, capsule of C. tricolor ; d, a ver- 

 tical section of its seed. 



Sub-order DichondrxE. — Carpels distinct. Dichondra. 



Sub-order Cuscutin^. — Embryo filiform, coiled spirally in 

 fleshy albumen, destitute of cotyledons. Parasitic, leafless, 

 twining herbs destitute of green color. Cuscuta. 



494. PoLEMONiACE/E, the PMox Tribe. — Herlaceous plants ; 

 stem occasionally climbing. Leaves opposite or alternate. Calyx 

 5-parted, persistent, sometimes irregular. Corolla regular, 

 5-lobed, festivation convolute. Stamens 5, inserted on the co- 

 rolla alternate with its segments. Ovary free, 3-celled ; ovules 

 few or many ; style simple ; stigma trifid. Fruit a 3-celled, 

 3-valved ^ capsule. Seeds angular, oval, or winged ; embryo 

 straight, in fleshy or horny albumen. 



Genera. — Phlox, Polemonium. 



495. DiAPENsiACE^. — Prostrate^ suffruticose ^plants. LeoAJes 

 evergreen, densely imbricated. Floioers solitary, terminal. Sej)- 

 als 5, much imbricated, scarcely distinguishable from the 

 bracts which are closely imbricated around'it. Corolla regular, 

 aestivation imlu'icated. Stame^is 5, equal ; filaments pet'aloid, 

 arising from the margin of the sinuses of the corolla ; anthers 

 transversely 2-valved. Ovary 3-celled. Fruit capsular. Seeds 

 many ; emhryo in fleshy albumen. 



Genera. — Diapensia, Pyxidanthera, 



496. SoLANACE^, the Potato Tribe. — Herbs or shrubs. 

 Leaves alternate, the floral ones sometimes double, and 

 crowded. Liflorescence variable. Calyx 5, seldom 4-parte(l, 

 persistent, inferior. Corolla plaited, or valvate in aestivation; 



