FAMILIES OF PLANTS 57 
conspicuous, without either calyx or corolla but with an 8- to 12-cleft 
involucre in place of a calyx. 
Hornwort (C eratophyllum demersum) grows in ponds or slow- 
flowing streams and has sessile leaves that are cut into thrice-forked, 
thread-like divisions and occur in whorls of 6 or 8. The flowers are 
imperfect. A staminate flower consists of 12 to 24 stamens and a 
pistillate flower consists of a single ovary only. 
BUTTERCUP EAMILY (RANUNCULACEAE) 
The buttercup family is a large family of plants with varying 
characteristics. None of them is of great economic importance 
except as ornamental plants, but many of them have beautiful and 
interesting flowers, and a few are poisonous when eaten by animals. 
They all agree in having all parts of the flowers distinct, however 
much they may differ in other ways. 
1. Flowers irregular. 2. 
1. Flowers regular. 3. 
2. Upper sepal spurred. Larkspur {Delphinium) _ (p. 57) 
2. Upper sepal hooded, helmetlike. Monkshood (AcomU/m columbianum)X p. 58) 
3. Sepals spurred. Leaves linear. Mousetail (Myosurus) _ (p. 58) 
3. Sepals not spurred. Leaves not linear. 4. 
4. Petals spurred. Columbine (Aquilegia) ______(p. 59) 
4. Petals not spurred. 5. 
5. Flowers subtended by an involucre. 6. 
5. Flowers not subtended by an involucre. 7. 
6. Flowers red. Styles short. Anemone (Anemone) _(p. 59) 
6. Flowers purple or white. Styles long and feathery. American pasque flower 
(Pulsatilla hirsutissima )_______(p. 60) 
7. Leaves opposite. Clematis {Clematis) ______ (p. 60) 
7. Leaves not opposite. 8. 
8. Flowers white. 9. 
8. Flowers yellow. 12. 
8. Flowers greenish. Meadowrue ( Thalictrum )_ (p. 61) 
9. Plants strictly aquatic. Water crowfoot ( Batrachium )_(p. 61) 
9. Plants not strictly aquatic though some may grow in very wet places. 10. 
10. Leaves compound. Baneberry (Actaea) ______ = -(p. 61) 
10. Leaves simple. 11. 
11. Leaves undivided. Marshmarigold {Caltha rotundifolia) _(p. 62) 
11. Leaves deeply lobed or divided. Globeflower (Trollius albiflorus)_ _(p. 62) 
12. Petals broad. Buttercup {Ranunculus) __ (p. 62) 
12. Petals narrow. Trailing buttercup (Halerpestes cymbalaria) ___(p. 62) 
Larkspur (Delphinium ).—The uppermost of the 5 sepals is de¬ 
veloped backward into a spur, and the 2 upper of the 4 petals are 
prolonged backward into a spur which is enclosed within the spur 
of the sepal. In some species there are only 2 petals, an upper 
and a lower. The stamens are numerous, but the pistils are few. 
Certain species are poisonous when eaten by cattle. 
