28 CELISTRACEAE. 



or acrid oil. Parts of the flower in 3s-5's. Stamens in ours as many as 

 the petals and alternate with them. Pistils 2-5, separate or united; 

 styles conniving. Fruit a capsule or a samara. 



Xanthoxylum. Flowers dioecious; fruit capsular. 

 Ptelba. Flowers polygamous; fruit a samara. 



XANTHOXYLUM L. Small trees with prickly branches and urnbel-like 

 clusters of flowers and odd-pinnate leaves. Calyx in ours wanting". Petals 

 4-5, imbricated in the bud. Pistils 3-5; styles distinct below but slightly 

 united above. Capaule coriaceous, 2-valved, with 1-2 black seeds. 



X. americanum Mill. Prickly Ash. Toothache-tree. A small shrub, 4-10 

 feet high, bark and leaves pungent and aromatic: leaflets 5-9, ovate-oblong, 

 pubescent when young; flowers * appearing before the leaves, yellowish 

 green, in sessile axillary umbels; capsules globose, short-stipitate. Upland 

 thickets; April-May; common generally. 



PTELEA L. Ours a small shrub, with 3-foliate, long-petioled leaves, the 

 leaflets sessile, crenulate, and corymbose-paniculate greenish white flowers. 

 Sepals and petals 3-5. Ovary flattened, 2-celled; stigmas 2. Samara orbicu- 

 lar, the wing membranous, reticulated, eraarginate. 



P. trifoliata L. Hop-tree. Woods; June; infrequent; Scott, Muscatine, 

 Lee, Henry, and Johnson counties. 



CELASTRACEAE Lindl. Staff-tree Family. 

 Small trees or shrubs, often climbing, with alternate or opposite sim^ 

 pie entire or toothed leaves, small caducous stipules, and small regular 

 flowers. Sepals and petals imbricated in the bud. Petals 4-5, alternate 

 with the sepals. Stamens 4-5, alternate with the petals, inserted on a 

 disk which fills the bottom of the calyx. Styles united, Ovary sessile, 

 2-5-celled, free from the calyx. 



Euonymus, Leaves opposite; a small tree. 

 CELAsrRirs. Leaves alternate; a shrubby climber. 



EyONYMUS L. Pepresented in our flora by the following species. 



E. atropurpureus Jacq. Burning Bush. Shrub 5-15 feet high; leaves 

 petioled, ovate-oblong, serrate, acuminate; flowers perfect, purple, solitary or 

 in axillary cymes, parts usually in 4's; styles short or none; pod deeply 3-4- 

 lobed, 3-4-valved, 3-4-celled, each cell 1-4-seeded; seeds covered with a scarlet 

 aril. Rich woods; June; frequent throughout the state. 



CELASTRUS L. Flowers small, dioecious or polygamous, small, greenish, 

 in terminal raceme-like clusters. Sepals, petals and stamens 5. Disk 5- 

 lobed, bearing the crenulate petals and stamens on the edge. 



C. scandens L. Climbing Bitter-sweet. Shrubby, climbing; leaves petioled, 

 ovate, thin, acuminate, serrate; pod globose, orange colored, 3-celled, 3- 

 valved, opening in the fall and displaying the scarlet covering of the seeds; 

 seeds 1-2 in each cell. Thickets; June; frequent. 



SIMARUBACEAE DC. Ailanthus Family. 



Distinguished from the preceeding order by the non-punctate leaves. 

 Represented in our flora by the genus Ailanthus Desf. 



A. glandulosa Desf. Tree-of-Hcavcn. Tree, 20-60 feet high, with long odd- 

 pinnate petioled leaves and greenish white polygamous panicled flowers; the 

 Btaminate flowers ill-scented; samaras oblong, membranous, 1-seeded, twisted. 

 Established in and about Keokuk, Lee county. 



