xxiv GENERAL KEY TO THE ORDERS AND FAMILIES. Vol.1. 



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. 1 : 578. 

 Leaves simple. 



Fruit 1 -seeded. Order 3. Myricales. 



Ovule erect, orthotropous. Fam. 3. Myricaceae. 1:584. 



Ovule laterally attached, ascending, amphitropous. Fam. 4. Leitneriaceae. 1 : 586. 



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



One family only. 



Fam. 5. Salicaceae. 1 : 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. 1 : 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. Ueticales. 

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



Trees with alternate leaves, the sap not milky. Fam. 8. Ulmaceae. 1:625. 



Trees with alternate leaves and milky sap. Fam. 9. Moraceae. 1 : 630. 



Fruit an achene ; herbs with small clustered greenish flowers. 



Ovule pendulous; styles or stigmas 2. Fam. 10. Cannabinaceae. 1 : 633. 



Ovule erect or ascending; style or stigma 1. Fam. 11. Urticaceae. 1 : 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. 1 : 638. 

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



Fam. 13. Santalaceae. 1 : 639. 

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



One family in our area. 



Fam. 14. Aristolochiaceae. 1 : 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. 1 : 646. 

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



Order 11. Chenopodtales {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. 2 : 25. 



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



Fam. 19. Corrigiolaceae. 2:26. 

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



Fam. 20. Nyctaginaceae. 

 Fruit a capsule, dehiscent by valves, or teeth. 



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



Capsule i-celled ; petals mostly present. 



Sepals 2. Fam. 22. Portulacaceae. 



Sepals 5 or 4, distinct or united. 



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



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



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). 



1. 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 1 ; petals none ; leaves whorled, dissected. Fam. 25. Ceratophyllaceae. 2:75. 



