IV. ANALYTICAL KEY TO THE NATURAL ORDERS 
OF THE PLANTS OF THE NORTHERN UNITED 
STATES. 
Series I. PHA5NOGAMOUS PLANTS. 
Class I. DICOTYLEDONOUS or EXOGENOUS PLANTS. 
Page 
Subclass I. ANGIOSPERM aE. Seeds in a pericarp. 2 
Div. I. POLYPETALOUS. Calyx and corolla both present j the 
petals distinct (separate). 2 
1. Ovary or ovaries one-celled. 
* Calyx free , or nearly so {not adherent ). 
•♦-Pistils coherent in an imbricated mass on the prolonged receptacle. 
Magnoliacece, 17 
-♦—-^Pistils immersed in the upper surface of the top-shaped receptacle. 
Nelumbiacea, 22 
Menispermacete, 19 
e 'l 
)• S 
Anonacea, 
Cabombacete. 
77 
Pistils 2 or more, distinct, unconnected. 
Stamens hypogynous, numerous or indefinite. 
Flowers dioecious or polygamous. 
Flowers perfect. 
Petals 6, in 2 rows, valvate. 
Petals 3-4, persistent, imbricated. 
Petals 4-many, often irregular or stamen-like. 
Stamens hypogynous, 5 or 10. 
Styles recurved, becoming lateral (Zanthorhiza) 
Styles conniving, 3-5. 
Stamens perigynous (on the base or throat of the calyx). 
Leaves with stipules, seeds destitute of albumen. 
Leaves destitute of proper stipules. 
Pistils fewer than the sepals or petals (2). Saxifragacea, 147 
Pistils, petals, and sepals equal in number (3-5). Crassulacea, 145 
Pistil only one, simple (of a single carpel). 
Stamens hypogynous, early deciduous. 
As many as the petals and opposite them : anthers ^ 
opening by uplifted valves. > Berberidacea, 20 
More numerous than the petals. (Podophyllum.) ) 
Also Actaea, Cimicifuga, &c., in Ranunculacea , 2 
Ranunculacea, 
Zanthoxylacea, 
Rosacea, 112 
Stamens perigynous. 
Flower regular. Fruit a drupe. Stamens many. Pomea, 112 
Flower regular. Fruit an acnenium. Stamens few. Sanzoisorbeee, 113 
Flower papilionaceous (or somewhat so). Fruit a pod. Leguminosa, 90 
—i—•— Pistil one, compound. 
Ovary with a free placenta in the centre, or 1 -few-ovuled from the base. 
Sepals 2 : petals 5. Portulacacea, 66 
Sepals or calyx-lobes as many as the petals (4-5). 
