16 
PLANTS OP YELLOWSTONE NATIONAL PARK 
88. Petals united. 89. 
88. Petals distinct or lacking. 95. 
89. Plants with milky juice. Dogbane ( Apocynum) _(p. 101) 
89. Plants without milky juice. 90. 
90. Ovary deeply 4-lobed. Borage family_(p. 105) 
90. Ovary not lobed. 91. 
91. Leaves whorled. Greengentian (Frasera speciosa) _(p. 101) 
91. Leaves opposite. 92. 
91. Leaves alternate. 93. 
92. Style branches 2. Gentian ( Gentiana) _ (p. 100) 
92. Style branches 3. Phlox (Phlox) _(p. 102) 
93. Style not lobed. 94. 
93. Style 2-lobed. Waterleaf family_ „__„(p. 104) 
93. Style 3-lobed. Phlox family_(p. 101) 
94. Leaves deeply lobed. Solarium triflorum _(p. 109) 
94. Leaves entire or irregularly toothed. Primrose family_(p. 99) 
95. Leaves opposite. 96. 
95. Leaves not opposite. 99. 
96. Flowers small, green, inconspicuous. Narrowleaf nettle (Urtica gra¬ 
cilis) _(p. 45) 
96. Flowers larger, conspicuously colored. 97. 
97. Flowers in umbels. Yellow sandverbena (Abronia ammophila) _(p. 53) 
97. Flowers not in umbels. 98. 
98. Sepals 2. Purslane family___(p. 54) 
98. Sepals 4 or 5. Pink family____(p. 55) 
99. Leaf bases forming a sheath at each joint of the stem. Buckwheat 
family_ (p. 48) 
99. Leaf bases not forming sheaths on the stem. 100. 
100. Stamens 2 or 4. Plantain ( Plantago) _(p. 114) 
100. Stamens 5. 101. 
100. Stamens 6. 106. 
100. Stamens 9. Eriogonum _(p. 48) 
100. Stamens 8 or 10. 107. 
100. Stamens more than 10. 111. 
101. Flowers white or whitish. 102. 
101. Flowers blue. Prairie flax (Linum lewisii) ___(p. 84) 
101. Flowers yellow. Horkelia gordonii ___(p. 76) 
101. Flowers greenish or purplish. 104. 
101. Flowers rose color. Alfileria (Erodium cicutarium) _(p. 83) 
102. Leaves mostly basal, not sessile. 103. 
102. Leaves not basal, sessile on the stem. Comandra pallida _(p. 47) 
103. Leaf blades clothed with reddish, gland-bearing hairs. Narrowleaf sundew 
(Drosera longifolia) ___(p. 69) 
103. Leaf blades not clothed with gland-bearing hairs. Saxifrage family. _ (p. 69) 
104. Leaves mostly basal. Alumroot (Heuchera) _(p. 71) 
104. Leaves not basal. 105. 
105. Petals pinnately lobed. Mitella pentandra _(p. 71) 
105. Petals lacking. Goosefoot family_(p. 52) 
106. Leaves not compound. Mustard family_(p. 64) 
106. Leaves compound with 3 leaflets. Bee-flower (Cleome serrulata) _(p. 69) 
107. Leaves fleshy. Stonecrop (Sedum) _(p. 69) 
107. Leaves not fleshy. 108. 
108. Pistils 2. Floerkia ___(p. 85) 
108. Pistil 1. 109. 
