180 RHAMNACEiE. 



with a cartilaginous testa, grooved longitudinally on the outer 

 side, the raphe in the groove. Embryo in the axis of fleshy 

 albumen, of about its length : cotyledons oval or orbicular, 

 foliaceous, parallel to the axis and the raphe, their margins 

 recurved on each side of the groove so as to become navicu- 

 lar : RADICLE very short, inferior, turned a little from the hilum. 

 Shrubs or small trees, sometimes with spinescent branches ; 

 the leaves mostly alternate, loosely pirniately veined. Stip- 

 ules linear or subulate, caducous. Flowers small, greenish, 

 axillary, usually fascicled or cymose-clustered, rarely race- 

 mose, either strictly polygamo-dioecious, or (as in R. lanceo- 

 latus) subdicEcions, both kinds of flowers with well-formed 

 stamens and often fruit-bearing, but the styles in the sub- 

 sterile flowers much shorter than in the others. 



Etymology. 'Pd^ivos, the ancient Greek name of the Buckthorn. 



Properties. Tlie fruit and bark are purgative. Those of the common 

 Buckthorn (R. catharticus, a European species, much used for hedges in the 

 Northern United States) are drastic. From their unripe fruit the water-color 

 called sap-green is prepared. " French berries," the fruit of R. infectorius, 

 &c., are employed in calico-printing, and in dying morocco leather yellow. 



Geographical Distribution. Principally natives of the Northern tem- 

 perate zone, the greater part belonging to the Old World. The only well- 

 determined species of the United States are R. lanceolatus (including R. 

 Shortii, Nutt., and R. parvifolius, Torr. <^ Gr.) and R. alnifolius, L^Her.; 

 the latter pentandrous, apetalous, the seeds with a shallow but manifest dorsal 

 groove and the cotyledons recurved in the manner characteristic of the genus. 



PLATE 168. Rhamnus lanceolatus, PwrsA. ; — Pennsylv., Pro/". Green. 



1. A flowering branchlet of the truly fertile plant, of the natural size. 



2. A similar flowering branchlet of the substerile plant. 



3. Diagram of the flower. (In the ovary the raphes are becoming lateral.) 



4. A flower (from Fig. 2), magnified ; and 5. with the calyx divided. 



6. A petal, spread out and more magnified. 



7. A magnified stamen seen from the outside, and 8. from the inside. 

 9. A truly fertile flower (from Fig. 1), magnified. 



10. Vertical section of the same, more magnified. 



11. A branch in fruit, of the natural size ; from the mountains of Virginia. 



12. Vertical section of a drupe through the seeds and embryo, magnified. 



13. Transverse section of the same, showing the recurved cotyledons, &c. 



14. A seed, the dorsal groove towards the eye, cut across, and magnified. 



15. Embryo spread out, magnified. (Cotyledons truly foliaceous.) 



