Jones: Flora of Illinois 9 



1 3. Leaves alternate. 



14. Leaves compound Section 13, p. 25 



14. Leaves simple. 



15. Leaves entire SECTION 14, p. 26 



15. Leaves toothed or lobed, not entire. 



16. Leaves lobed SECTION 15, p. 27 



16. Leaves toothed, but not lobed SECTION 16, p. 28 



12. Flowers on leafless or almost leafless twigs, appearing before the leaves (or in 

 autumn when they are falling, in H amamelis) SECTION 17, p. 29 



Group II. Ferns and Fern-allies. Plants without flowers or seeds, reproducing by spores 

 borne in sporangia Section 18, p. 30 



Key to the Families 



Section \. Grasses (or Grass-like Plants), or Sedges, and Rushes 



1. Flowers enclosed by chaffy scales; perianth none, or of bristles; fruit a grain or an 

 achene. 

 2. Stem usually cylindrical, usually hollow except at the nodes; leaves in 2 rows on 

 the stem, the sheaths usually split; fruit usually a grain 22. Gramineae 



2. Stem cylindrical or triangular, solid, the nodes usually not conspicuous; leaves in 3 



rows on the stem, the sheaths not split; fruit an achene 23. Cyperaceae 



1. Flowers not enclosed by chaffy scales; perianth 6-parted; stems terete; fruit a capsule. 



3. Stem not glandular 30. Juncaceae 



3. Stem glandular Tofieldia in 3 1 . LiLIACEAE 



Section 2. Herbs with Compound (or Deeply Divided) Leaves 



I . Plants without leafy stems, the leaves all basal and the flowering stems leafless. 



2. Leaves 2-cleft; flowers white; fruit a capsule opening by a lid 



Jeffersonia in 66. Berberidaceae 



2. Leaflets 3 or more; fruit not opening by a lid. 



3. Flowers on a spadix surrounded by a spathe ; fruit a berry 



Arisaema in 24. AracEAE 



3. Flowers in racemes or umbels. 

 4. Leaflets 3. 



5. Leaflets entire; flowers regular; stamens 10 86. OXALIDACEAE 



5. Leaflets not entire. 



6. Flowers papilionaceous; stamens 10 84. Leguminosae 



6. Flowers regular; stamens numerous 83. RosACEAE 



4. Leaflets numerous; flowers irregular 70. FuMARIACEAE 



1 . Plants with stems bearing 1 or more leaves. 



7. Flowers borne in a dense head on a common receptacle surrounded or subtended by 



an involucre of bracts; fruit an achene; stipules none 152. CoMPOSITAE 



7. Flowers not borne in a dense head on a common receptacle surrounded or subtended 

 by an involucre. 



8. Flowers on a spadix surrounded by a spathe; fruit a berry 



Arisaema in 24. Araceae 



8. Flowers not borne on a spadix surrounded by a spathe. 

 9. Flowers in umbels; petals 5; stamens 5; ovary inferior. 



10. Fruit dry, composed of 2 carpels; styles 2 119. Umbelliferae 



10. Fruit a berry; styles 5. or 3, or 2 118. AraliacEAE 



9. Flowers not in umbels, or if so, the flowers not as above in all respects. 



11. Corolla papilionaceous; fruit a legume or loment; leaves alternate, usually 



stipulate 84. Leguminosae 



11. Corolla not papilionaceous. 



12. Stem bearing only a single leaf or a pair or whorl of leaves. 



13. Sepals and petals each 4; fruit a pod; leaflets 3 or 5, toothed 



Dentaria in 71. Cruciferae 



