36 American Midland Naturalist Monograph No. 7 



9. Anthers opening by apical pores; pith of the branches soHd 



93. Ericaceae 



9. Anthers opening lengthwise; flowers white or greenish. 

 10. Pith chambered, or separated by woody plates. 



11. Leaves stellate-pubescent beneath; flowers perfect, white, 

 nodding, on slender pedicels; calyx 4-toothed; petals 

 4, united below; fruit dry, bony within, 1-seeded, 4- 



winged Halesia in 95. Styracaceae 



11. Leaves not stellate-pubescent. 



12. Flowers greenish, unisexual; fruit a drupe 



- Nyssa in 90. Cornaceae 



12. Flowers white, perfect; fruit a 2-valved, ellipsoid, 2- 

 loculed, several-seeded capsule tipped with the 2 



styles 56. Escalloniaceae 



10. Pith solid. 



13. Stems climbing, twining or trailing; leaves elliptical to 

 roundish, finely serrate, glabrous; flowers in terminal 

 racemes; capsules subglobose, yellow, with crimson 



seeds Celastrus in 44. Celastraceae 



13. Stems erect. 



14. Flowers solitary or clustered in the axils; fruit a 



small, berry-like drupe with 4-8 bony nutlets 



48. Aquifoliaceae 



14. Flowers in small dense panicles or corymbs; fruit a 3- 



loculed capsule, or drupaceous 51. Rhamnageae 



8. Stamens 15 or more; fruit a drupe, pome, or follicle 



53. ROSACEAE 



6. Leaves with 3 or more principal veins from the base. 



15. Leaves cordate, slender-petioled, abruptly acuminate, sharply 



serrate; trees 22. Tiliaceae 



15. Leaves not cordate. 



16. Low shrub; pith continuous; flowers white; fruit a capsule; 

 leaves ovate or elliptic-lanceolate, short-petioled, finely 



toothed Ceanothus in 51. Rhamnaceae 



16. Trees or shrubs; pith of branches chambered; flowers greenish, 

 apetalous; fruit a red drupe; leaves ovate-lanceolate or lance- 

 olate, acuminate, scabrous Celtis in 70. Ulmaceae 



1. Base of blade noticeably asymmetrical. 



17. Leaves sinuately or obtusely toothed, obovate or oval; flowers appearing 

 in autumn when the leaves are falling; petals 4, yellow, linear; calyx 



4-parted; stamens 8, short; styles 2; fruit a capsule 



Hamamelis in 58. Hamamelidaceae 



17. Leaves serrate; flowers appearing in spring; fruit not a capsule. 



18. Leaves cordate, glabrous, or the lower surface pubescent or with 

 tufts of hairs in the axils of the veins; flov/ers appearing after the 

 leaves, in drooping cymes, small, fragrant, the peduncle united 



with the membranous bract: fruit small, globose indehiscent 



22. Tiliaceae 



18. Leaves scabrous or hispidulous; flowers apetalous, appearing with or 

 before the leaves. 



19. Flowers in catkins; leaf-buds acute Ostrya in 66. Betulaceae 



19. Flowers not in catkins; leaf-buds obtuse 70. Ulmaceae 



