148 ZANTIiOXYLACE^. 



cles as there are pistils, or by abortion fewer, sessile or stipi- 

 tate, punctate, one - two-seeded, splitting down the ventral 

 suture, or at length two-valved. Seed pendulous from the 

 apex of the placental edge of the carpel, which inclines to 

 separate from the valves, between amphitropous and anatro- 

 pous, ovoid or globular, black and shining ; the testa thin 

 and a little fleshy, at length brittle and transparent, covering 

 a thick crustaceous integument. Ejibryo straight, in the 

 axis of fleshy albumen and nearly of its length : coxrLEDONs 

 broadly oval or orbicular, foliaceous : radicle short, superior. 

 Trees or shrubs, commonly armed with stipular prickles ; 

 the alternate or rarely opposite leaves mostly pinnate, often 

 fascicled ; the petiole sometimes prickly, rarely alate ; the leaf- 

 lets entire or serrulate, punctate with pellucid dots. Flowers 

 small, greenish or whitish, fasciculate, spicate, or cymose, 

 the clusters or cymes axillary or terminal. 



Etymology. Name from ^av66s, yeUoio, and ^vkov, wood. Xanihoxylum 

 is the proper orthography, but the other form was adopted by Linnaeus. 



Note. The genus was founded on our Northern Prickly Ash, here figured, 

 which has a single perianth, usually described as a calyx. But as the stamens 

 alternate with its parts, just as with the petals of Z. Carolinianum, I take it 

 for the corolla, and suppose that the calyx is abortive. Our subgenera are : 



§ 1. EuzANTHOXYLUM. (Zanthoxylum, Colden.) — Calyx abortive. Petals 

 (bearded at the tip), stamens, and pistils 5. Flowers in lateral fascicles. 



1^ 2. OcHROxYLUM. — Sepals, petals, and stamens 5. Pistils 3. 



^3. Pterota. — Sepals, petals, and stamens 4. Pistils 1-2. Petiole 

 winded. 



PLATE 15fi. Zanthoxylum Americanum, Mill.; — branch of a stami- 

 nate plant in flower, and of a pistillate plant taken a little later. 

 1. A pistillate flower; 2. a staminate flower, enlarged. 



3. Vertical section of the latter, showing the abortive pistils, &c. 



4. Enlarged pistillate flower, with the perianth laid open. 



5. Vertical section of one of the pistils, magnified, showing one ovule. 



6. Transverse section of an ovary, through both ovules, magnified. 



7. An ovule, more magnified. 



8. Fruit, of the natural size. (Two pistils abortive, the others stipitate.) 



9. The same enlarged, two carpels dehiscent. 10. A seed, magnified. 

 11. Vertical, and 12. transverse section of the seed and embryo, magnified. 



13. Diagram of a staminate flower of Zanthoxylum Carolinianum. 



14. Expanded staminate flower of the same, magnified. 



