CONSPECTUS OF NORTH AMERICAN SPECIES OF VITIS.
A. Skin of mature berry separating freely from the pulp. B. Nodes without diaphragms; tendrils simple =1. V. rotundifolia.= =2. V. munsoniana.=
B.B. Nodes with diaphragms; tendrils forked.
C. Leaves and shoots glabrous at maturity and without bloom. Tendrils intermittent (_V. cinerea_ and _V. arizonica_ are partial exceptions and might be looked for under C.C.).
D. Leaves thin, light, bright green, generally glabrous below at maturity except perhaps in the axils of the veins (_V. champini_ an exception) with a long or at least a prominent point and usually long and sharp teeth or the edge even jagged. (_V. bicolor_ might be looked for here.)
E. Leaves broader than long; petiolar sinus usually wide and shallow. (_V. treleasei_ might be sought here.) =3. V. rupestris.=
E.E. Leaves ovate in outline; petiolar sinus usually medium to narrow.
F. Diaphragms thin; young shoots not red.=4. V. monticola.= =5. V. riparia.= =6. V. treleasei.= =7. V. longii.= =8. V. champini.= F.F. Diaphragms thick; young shoots bright red =9. V. rubra.=
D.D. Leaves thickish, dull colored or grayish green, often holding some close dull pubescence below at maturity, shoots and leaves nearly always more or less pubescent when young; the teeth mostly short; the point mostly rectangular and conspicuous.
E. Plants strong, climbing, with stout persistent tendrils.
F. Young shoots cylindrical, glabrous or very soon becoming so =10. V. cordifolia.=
F.F. Young shoots angled, covered the first year with tomentum or wool =11. V. baileyana.= =12. V. berlandieri.= =13. V. cinerea.=
E.E. Plants scarcely climbing, tendrils perishing when without support =14. V. arizonica.=
D.D.D. Leaves orbicular, scallop shaped; species of the Pacific Coast =15. V. californica.=
C.C. Leaves rusty or white tomentose or glaucous blue below, thick or at least firm. (_V. cinerea_, _V. arizonica_ and possibly _V. californica_ might be sought here.)
D. Leaves flocculent or cobwebby or glaucous below when fully grown (i. e. not covered with a thick dense felt-like tomentum except sometimes in _V. doaniana_).
E. Shoots white tipped; ends of the growing shoots and the under surface of the leaves whitish or gray =16. V. girdiana.= =17. V. doaniana.=