BOTANY. 171 



a, flowering branch ; b, male flower ; c, anther ; d, female flowers ; 6, pistil ; 

 /, fruit ; g, section of ditto. 



■ Order 158. Ruamnace^, the Buckthorn Family. Calyx four- or five- 

 cleft, valvate in aestivation. Petals distinct, hooded, or convolute, inserted 

 into the throat of the calyx, sometimes 0. Stamens definite, opposite the 

 petals. Disk large, fleshy, flat, or urceolate. Ovary superior or half 

 superior, two-, three-, or four-celled ; ovules solitary, erect, anatropal. 

 Fruit fleshy and indehiscent, or dry and separating into three parts. Seeds 

 erect ; albumen fleshy, rarely ; embryo about as long as the seed, with a 

 short inferior radicle, and large flat cotyledons. Trees or shrubs, often 

 spiny, with simple, alternate, rarely opposite leaves, and minute stipules. 

 They are generally distributed over the globe, and are found both in 

 temperate and tropical regions. There are 43 genera and 250 species 

 enumerated. Of these four genera and thirty-four species are cited as 

 North American by Torrey and Gray. 



Tnbe 1. Paliureoe. Shrubs of the Old World with alternate leaves. 

 Fruit semi-adherent, dry, crowned by a transversely circular wing. 

 Example: Yentilago. 



Tribe 2. Frangulece. Trees or shrubs spread over the temperate zones ; 

 with alternate leaves. Fruit without wings, free or semi-adherent, fleshy 

 or capsular, with the shell indehiscent or opening by an internal fissure. 

 Examples : *Berchemia, *Sageretia, *Rhamnus, *Ceanothus. 



Tribe 3. Pomaderreoe. Unarmed Australian shrubs with alternate leaves. 

 Fruit wingless, capsular, the shell opening by an introrse perforation, covered 

 by a membrane. Example : Trymalium. 



Tribe 4. Colletiece. Shrubs of temperate South America, the branches 

 terminated by a spine, leaves decussate, sometimes almost none. Fruit 

 wingless, free. Example : Colletia. 



Tribe 5. PhylicecB. Shrubs of the Cape and of extra-tropical Australia ; 

 unarmed, leaves alternate. Fruit wingless, adherent, and crowned by the 

 calyx, capsular. Example : Spyridium. 



Tribe 6. Oouanieoe. Lianas or herbs of the tropics, or of South Africa ; 

 unarmed. Fruit adherent, separating by shells usually winged longi- 

 tudinally on the back, opening by an internal fissure. Example : 

 Helinus. 



E-hamnus catharticus or the Buckthorn, naturalized in the United States, 

 is sometimes used medicinally. The greenish juice, when mixed with lime 

 and evaporated to dryness, forms the color called sap green. French berries 

 used in dyeing yellow are obtained from R. infectorius. Various species are 

 native in North America. Jujube is the fruit of Zizyphus jujuba. The 

 Lotus of the ancients is a second species, Z. lotus. The leaves of Ceanothus 

 americanus were used in the revolutionary war as a substitute for tea. 



Rhamnus catharticus. Buckthorn (Europe) {pi. 11, ßg. T); «, a flowering 

 branch ; J, a male ; c, a female flower ; d, a fruit ; e, ditto with part of the 

 flesh removed ; y, the seed; g, do. in cross-section. 



Order 159. Staphyleace^, the Bladder-nut Family. Sepals five, united 



171 



