RHAMNACE^. (BUCKTHORN FAMILY.) Ill 



Order 27. RHAMNACE.^. (Buckthorn Family.) 



Shrubs or small trees, with simple leaves, small and regular /lowers (some- 

 times apetalous), tuith the A or b perigynous stamens as many as the valcule 

 sepals and alternate loith them, accordingly opposite the petals! Drupe or 

 pod icith only one erect seed in each cell, not arilled. — Petals folded in- 

 wards in the bud, liooded or concave, inserted along with the stamens 

 into the edge of the fleshy disk which lines the short tube of the calyx 

 and sometimes unites it to the lower part of the 2-5-celled ovary 

 Ovules solitary, anatropous. Stigmas 2 - 5. Embryo large, with broad 

 cotyledons, in sparing fleshy albumen. — Flowers often polygamous, some- 

 times dioecious. Leaves mostly alternate ; stipules small or obsolete. 

 Branches often thorny. (Slightly bitter and astringent ; the fruit often 

 mucilaginous, commonly rather nauseous or drastic.) 

 * Calj'x and disk free from the ovary. 



1. Berchemia. Petals sessile, entire, as long as the calyx. Drupe with thin flesh and a 



2-celled bony putunien. 



2. Rliamnus. Petals small, short-clawed, notched, or none. Drupe berry-like, with 2-4 



separate seed-like nutlets. 



* * Calyx with the disk adherent to the base of the ovary. 



3. Ceanothus. Petals long-clawed, hooded. Fruit dry, at length dehiscent. 



1. BERCHEMIA, Necker. Supple-Jack. 



Calyx with a very short and roundish tube ; its lobes equalling the 5 oblong 

 sessile acute petals, longer than the stamens. Disk very thick and flat, filling 

 the calyx-tube and covering the ovary. Drupe oblong, with thin Hesh and a 

 bony 2-celled putamen. — Woody high-climbing twiners, with the pinnate veins 

 of the leaves straight and parallel, the small greenish-white flowers in small 

 panicles. (Name unexplained, probably personal.) 



1. B. volubilis, DC. Glabrous; leaves oblong-ovate, acute, scarcely 

 serrulate ; style short. — Damp soils, Va. to Ky. and Mo., and southward. 

 June. — Ascending tall trees. Stems tough and very lithe, whence the pop- 

 ular name. 



2. BHAMNUS, Tourn. Buckthorn. 



Calyx 4 - 5-cleft ; the tube campanulate, lined with the disk. Petals small, 

 short-clawed, notched at the end, wrapped around the short stamens, or some- 

 times none. Ovary free, 2-4-ceUed. Drupe berry -like (black), containing 

 2-4 separate seed-like nutlets, of cartilaginous texture. — Shrubs or small 

 trees, with loosely pinnately veined leaves, and greenish polygamous or dioe- 

 cious flowers, in axillary clusters. (The ancient Greek name.) 



§ 1. RHAMNUS proper. Flowers usually dioecious; nutlets and seeds deeply 

 grooved on the back; rhaphe dorsal; cotyledons Joliaceous, the 7na7-gins 

 revolute. 



* Calyx-lobes and stamens 5; petals wanting. 



1. R. alnifblia, L'Her. A low shrub; leaves oval, acute, serrate, nearly 

 straight-veiued ; fruit 3-seeded. — Swamps, Maine to Peun., Neb., and north- 

 ward. June 



