xxiv GENERAL KEY TO THE ORDERS AND FAMILIES. VOL. I. 



One family only. 



Fam. i. Saururaceae. i : 577. 

 Trees or shrubs; staminate flowers, and sometimes also the pistillate, in aments. 



Leaves odd-pinnate; fruit a nut enclosed in a husk. Order 2. JUGLANDALES. 



One family only. 



Fam. 2. Juglandaceae. i : 578. 

 Leaves simple. 



Fruit i-seeded. Orders. MYRICALES. 



Ovule erect, orthotropous. Fam. 3. Myricaceae. i : 584. 



Ovule laterally attached, ascending, amphitropous. Fam. 4. Leitneriaceae. i : 586. 



Fruit many-seeded ; seeds with a tuft of hairs at one end. Order 4. SALICALES. 



One family only. 



Fam. 5. Salicaceae. i : 587. 

 2. Calyx present. 

 * Flowers, at least the staminate ones, in aments. 



Order 5. FAGALES. 



Both staminate and pistillate flowers in aments. Fam. 6. Betulaceae. i : 605. 



Pistillate flowers subtended by an involucre, which becomes a bur or a cup in fruit. 



Fam. 7. Fagaceae. 1:614. 

 ** Flowers not in aments (in ament-like spikes in Morus), but variously clustered, rarely solitary. 



a. Flowers monoecious, dioecious or polygamous (sometimes perfect in Ulmus) ; 

 ovary superior, i -celled. 



Order 6. URTICALES. 

 Fruit not an achene ; trees, shrubs or herbs ; ovule pendulous. 



Trees with alternate leaves, the sap not milky. Fam. 8. Ulmaceae. i : 625. 



Trees with alternate leaves and milky sap. Fam. 9. Moraceae. i : 630. 



Fruit an achene ; herbs with small clustered greenish flowers. 



Ovule pendulous; styles or stigmas 2. Fam. 10. Cannabinaceae. i : 633. 



Ovule erect or ascending; s-tyle or stigma i. Fam. n. Urticaceae. i : 634. 



(Order 7, PROTEALES, extensively developed in the southern hemisphere, is not represented in 

 our area.) 



b. Flowers dioecious, or perfect ; ovary inferior, at least in part. 



Ovary i-celled. Order 8. SANTALALES. 



Tree-parasites, with opposite leaves or scales; fruit a berry. Fam. 12. Loranthaceae. i : 638. 

 Root-parasites, or shrubs ; leaves alternate in our genera ; fruit a drupe, or nut. 



Fam. 13. Santalaceae. i : 639. 



Ovary several- (usually 6-) celled; flowers perfect. Order 9. ARISTOLOCHIALES. 



One family in our area. 



Fam. 14. Aristolochiaceae. I : 641. 



C. Flowers mostly perfect in our genera (dioecious in some species of Rumex in Polygonaceae, 



monoecious or dioecious in some Chenopodiaceae and Amaranthaceae) ; ovary superior. 



t Embryo straight, or nearly so ; fruit an achene. 



Order 10. POLYGONALES. 

 One family. 



Fam. 15. Polygonaceae. i : 646. 

 tt Embryo coiled, curved, or annular ; fruit not an achene. 



Order ii. CHENOPODIALES (Centrospermae). 

 Fruit a utricle ; stipules none 



Bracts and sepals scarious. Fam. 16. Amaranthaceae. 2:1. 



Bracts none, or not scarious. Fam. 17. Chenopodiaceae. 2: 8. 



Fruit a berry in our genus. Fam. 18. Phytolaccaceae. 



Fruit a utricle ; stipules present (except in Scleranthus which has subulate, opposite connate leav 



Fam. 19. Corrigiolaceae. 



Fruit an anthocarp, the persistent base of the corolla-like calyx enclosing a utricle. 



Fruit a capsule, dehiscent by valves, or teeth. 



Fam. 20. Nyctaginaceae. 



Capsule 2-several-celled ; petals none. Fam. 21. Aizoaceae. 2 

 Capsule i -celled; petals mostly present. 



Sepals 2. Fam. 22. Portulacaceae. 2 

 Sepals 5 or 4, distinct or united. 



Sepals distinct ; ovary sessile. Fam. 23. Alsinaceae. z 



Sepals united ; ovary stipitate. Fam. 24. Caryophyllaceae. 2 



25- 

 es). 

 26. 



30. 

 34- 

 35- 



4i. 



61. 



B. Petals present (wanting in Ceratophyllaceae aquatic herbs with whorled dissected leaves; in 

 many Ranunculaceae ; in Calycocarpum a dioecious vine of the Menispermaceae ; in Laura- 

 ceae alternate-leaved aromatic trees and shrubs ; in Podostemaceae aquatic herbs, the 

 simple flowers involucrate ; in Liquidambar a tree with palmately-lobed leaves and capitate 

 flowers of the Hamamelidaceae in Sanguisorba herbs with pinnate leaves of the Rosaceae ; 

 in Xanthoxylum trees with pinnate leaves of the Rutaceae ; in Euphorbiaceae ; in Callitrich- 

 aceae, Empetraceae and Buxaceae ; in some of the Aceraceae and Rhamnaceae ; in Thymele- 

 aceae, Elaeagnaceae, and in some species of Ludwigia in Onagraceae and of Nyssa in Cor- 

 naceae). 



I. Ovary superior, free from the calyx (partly or wholly inferior in some Saxifragaceae, 

 in Grossulariaceae, Hamamelidaceae, Malaceae and Loasaceae). 



i. Carpels solitary, or several or distinct (united in Nymphaeaceae) ; stamens mostly hypogynous 

 and more numerous than the sepals; sepals mostly distinct. Order 12. RANALES. 



* Aquatic herbs; floating leaves if present, peltate, or with a basal sinus. 

 Pistil i ; petals none ; leaves whorled, dissected. Fam. 25. Ceratophyllaceae. 2 : 75. 



