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similar qualities. Conv. Jalapa produces the real jalap, and C. Scammonia 

 the scammony ; besides which, C. Turpethum, C. Mechoacanus, sepium, 

 arvensis, Soldanella, macrorhizus, maritimus, macrocarpus, and probably many 

 others, may be used with nearly equal advantage. The root of Convolvulus 

 panduratus is used in the United States as jalap ; its operation is like that of 

 rhubarb; it is supposed to be also diuretic. Barton, 1.252. The roots of 

 Conv. florid us and scoparius, and Ipomoea duamoclit, are used as sternuta- 

 tories ; those of C. Batatas and edulis are useful articles of food : the former 

 is the common sweet Potato of European gardens. The Cuscutas are 

 remarkable for becoming parasitical after having originally germinated in the 

 ground, from which they derive their nourishment until they fix themselves 

 firmly upon the plant that is finally to maintain them. 

 Examples. Convolvulus, Evolvulus, Falkia. 



CC. POLEMONIACEiE. The Greek Valerian Tribe. 



Polemonia, Juss. Gen. 136. (1789).— Polemonide*:, Dec. and Duby. 329. (1828).— Polemoni- 

 ace«, Lindl. Synops. 168. (1829).— Cob.eace.k, Don in Ed. Ph. Journ. 10. 111. (1824); 

 Link Handb. 1. 822. (1829.) 



Diagnosis. Monopetalous dicotyledons, with regular flowers, a superior 

 3-celled ovarium, peltate or ascending ovules, and a pentandrous 5-parted 

 corolla, with imbricated aestivation. 



Anomalies. Cobrea has a climbing habit. 



Essential Characteh. — Calyx inferior, monoscpalous, 5-parted, persistent, sometimes 

 irregular. Corolla regular, 5-lobcd. Stamens 5, inserted into the middle of the tube of the 

 corolla, and alternate with its segments. Ovarium superior, 3-celled, with a few or many 

 ovula; style simple; stigma trifid; ovules ascending or peltate. Capsuled celled, 3-valved, 

 few- or many-seeded, with a loculicidal or septicidal dehiscence ; the valves separating from 

 the axis. Seeds angular or oval, or winged, often enveloped in mucus, ascending ; embryo 

 straight in the axis of horny albumen ; radicle inferior ; cotyledons elliptical, foliaceous. — ■ 

 Herbaceous plants, with opposite, or occasionally alternate, compound, or simple leaves; 

 ■stem occasionally climbing. 



Affinities. The ternary division of the ovarium connected with the pen- 

 tandrous corolla and 5-lobed calyx bring this order near Convolvulaceae, from 

 which the habit, embryo, and corolla, distinguish it ; from Gentianeee, to which 

 it also approaches, the 3-celled ovarium divides it. It is remarkable for the 

 blue colour of the pollen, which is usually of that hue, whatever may be the 

 colour of the corolla. In Collomia linearis I have noticed (in Botanical Regis- 

 ter, folio 1166,) that the dilatation of the mucous matter in which the seeds are 

 enveloped, and which, when they are thrown into water forms around them 

 like a cloud, depends upon the presence of an infinite multitude of exceedingly 

 delicate and minute spiral vessels, lying coiled up, spire within spire, on the 

 outside of the testa ; when dry, these vessels are confined upon the surface of 

 the seed by its mucus, without being able to manifest themselves ; but the 

 instant water is applied, the mucus dissolves and ceases to counteract the 

 elasticity of the spiral vessels, which then dart forward at right angles with 

 the testa, each carrying with it a sheath of mucus, in which it for a long time 

 remains enveloped as if in a membranous case. I know of no parallel to this, 

 except in Casuarina, in which the whole of the inside of the testa consists of 

 minute spiral vessels. 



Geography. Very abundant in both North and South America, in tem- 

 perate latitudes, particularly on the north-west side. It is stated by Dr. Rich- 



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