x GENERAL KEY TO THE ORDERS AND FAMILIES. 



2. Calyx present. 

 4f Flowers, at least the staminate ones, in aments. Order 5. FAGALES. 

 Both staminate and pistillate flowers in aments. Fam. 6. Betidaceae. 1:506. 



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



Fam. 7. Fagaceae. 1:513. 

 X- & 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, 1 -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. 1:523. 



Trees with alternate leaves and milky sap; or opposite-leaved herbs or herbaceous vines. 



Fam. 9. Moraceae. 1: 527. 

 Fruit an achene; herbs with small clustered greenish flowers; ovule erect or ascending. 



Fam. 10. Urticaceae, z: 530. 



(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. 11. Loranthaceae. 1: 534. 



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



Fam. 12. Santalaceae. 1: 536. 

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



One family in our area. Fam. 13. Aristolochiaceae. 1:537. 



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. 

 | Embryo straight, or nearly so; fruit an achene. Order 10. PolygonaleS. 



One family. Fam. 14. Polygonaceae. 1: 541. 



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



Order 11. Chenopodiales {Centrospermae). 

 Fruit a utricle (see also last genera of Caryophyllaceae). 



Flowers bractless, or, if bracted, the bracts not scarious; sepals green, or greenish. 



Fam. 15. Chenopodiaceae. 1: 569. 

 Flowers bracted, the bracts, and also the sepals mostly scarious. 



Fam. 16. Amaranthaceae. 1: 586. 

 Fruit fleshy, enclosing several carpels; a berry. Fam. 17. Phytolaccaceae. I: 593. 



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



Fam. 18. Nyctaginaceae. 1:594. 

 Fruit a capsule, dehiscent by valves, or teeth (utricular in Anychia, Paronychia and Scleranthus 

 of the Caryophyllaceae). 

 Capsule 2-several-celled: petals none. Fam. 19. Aizoaceae. 1:597. 



Capsule i-celled; petals mostly present. 



Sepals 2. Fam. 20. Portulacaceae. 2: 1. 



Sepals 5 or 4, distinct or united. Fam. 21. Caryophyllaceae. 2: 6. 



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 sim- 

 ple 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 Ludzuigia 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, Pomaceae and Loasaceae). 



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

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



75- Aquatic herbs ; floating leaves peltate, or with a basal sinus. 

 Carpels 3, or more; petals large; floating leaves not dissected. Fam. 22. Nymphaeaceae. 2:41. 



Pistil 1 ; petals none ; leaves whorled, all submersed and dissected. Fam. 23. Ceratophyllaceae. 2: 46. 



Sf r Land or marsh plants (some Ranunculaceae aquatic). 



Stamens numerous; sepals distinct; petals present (except in some Ranunculaceae and in Calyco- 

 carpum of the Menispermaceae). 

 Receptacle not hollow; leaves alternate (except in Clematis). 



Flowers perfect (except in some species of Clematis and Thaliclrum). 



P'ruit aggregate, cone-like; trees; sepals and petals in 3 series, or more, of 3. 



Fam. 24. JMagnoliaaac. 2: 47. 

 Fruit not aggregate, the carpels separate, at least when mature. 

 Anthers not opening by valves; pistils usually more than 1. 



Sepals 3; petals 6; shrubs or trees. Fam. 25. Anonaceac. 2:49. 



Sepals 3-15: petals (when present) about as many; our species herbs or vines 

 (Xanikorrhiza. shrubby). Fam. 26. Ranunculaceae. 2:50. 



Anthers opening by valves (except in Podophyllum ); pistil 1 



Fam. 27. Berbcridaceae. 2: S9. 

 Dioecious climbing vines with simple leaves; fruit drupaceous. 



Fam, 28. Menispermaceae. 2: 93. 

 Receptacle hollow, enclosing the numerous pistils and achenes; opposite-leaved shrubs. 



Fam. 29. Calvtautliaceae. 2: 94. 



Stamens 9 or 12, in 3 or 4 series of 3; anthers opening by valves; aromatic trees or shrubs with no 



petals, more or less united sepals, and 1 pistil. Fam. 30. Lauraceae. 2: 95. 



