CHAPTER I. 



KEY FOR FAMILIES. 



I. Plants without true flowers; not producing seeds. . .Pteridophyta. 

 Stems jointed, rushlike Equisetaceae. 



I. Plants with true flowers, stamens, and pistils and producing seeds. 



Spermatophyta. 



II. Ovules not borne in a closed ovary (Pine, Spruce) 



Gymnospermae. 



II. Ovules borne in a closed ovary (Rose, Willow, Corn, etc.) 



Angiospermae. 



III. Stems endogenous without central pith; no annual rings; 

 parts of the flower usually in threes; single cotyledon... 



Monocotyledoneae. 

 1. Grasslike plants 2. 



2. Flowers enclosed by chaff-like scales. 



Stems hollow; sheaths of leaves split.. .Gramineae. 



Stems solid; sheaths of leaves not split. Cyperaceae. 



2. Flowers not inclosed by chaff -like scales. .Juncaceae. 



1. Plants not grasslike; flowers with a perianth of 6 



pieces; stamens 6 Liliaceae. 



III. Stem formed of bark, wood, and pith, exogenous; leaves 



netted-veined ; embryo with a pair of cotyledons 



Dicotyledoneae. 

 1. Corolla absent 



2. Plants fleshy or scurfy Chenopodiaceae. 



2. Plants not fleshy or scurfy 3. 

 3. Ovary free 4. 



4. Flowers unisexual. 



Ovary 1-celled TJrticaceae. 



Ovary 3-celled Euphorbiaceae. 



4. Flowers perfect. 



Calyx and bracts greenish and scarious 



Amaranthaceae. 

 Calyx generally corolla-like. 



1. Fruit a 1-seeded achene Polygonaceae. 



1. Fruit a 5-12 seeded berry. . .Phytolaccaceae. 



3. Ovary inferior Nyctaginaceae. 



1. Calyx and corolla present. 

 2. Corolla of separate petals 3. 



3. Plants fleshy, flowers yellow Portulacaceae. 



