402 PLANT MORPHOLOGY 



difference between this order and the Ranales. The Cruciferae are a 

 distinct family whose members can be recognized by the floral formula 

 4-4-6-2. 



Sarraceniales. This is a small order of insectivorous plants, compris- 

 ing 3 families, and represented by the pitcher plants {Sarracenia and 

 others) and the sundews (Drosera). As in the Papaverales, the flowers 

 are regular, hypogynous, and syncarpous. The two orders seem to have 

 undergone a parallel development, the chief difference between them 

 being the placentation. 



Resales. The Rosales constitute the great central order of Archi- 

 chlamydeae. They include 16 families and 15,000 species of herbs, 

 shrubs, and trees distributed throughout the world. The three chief 

 families are the Saxifragaceae, Rosaceae, and Leguminosae. The Legu- 

 minosae, with 12,000 species, is the second largest family of dicotyledons. 

 The Saxifragaceae are represented by the saxifrages (Saxifraga), goose- 

 berries and currants (Rihes), and Hydrangea. The Rosaceae include the 

 roses (Rosa), strawberries {Fragaria), raspberries and blackberries 

 (Ruhus), cherries and plums (Prunus), hawthorns (Crataegus), pear 

 and apple (Pijrus), etc. The Leguminosae include the acacias, locust 

 (Robinia), lupines (Lwpinus), clovers (Trijolium), beans (Phaseolus), peas 

 (Pisum), etc. 



The Rosales overlap the Ranales, on the one hand, with regularity, 

 hypogyny, apocarpy, and indefinite numbers of stamens and carpels, but 

 advance far beyond them, on the other hand, with irregularity, epigyny, 

 syncarpy, and definite numbers. The perianth is typically pentamerous. 

 The Rosaceae have regular flowers that are perigynous or epigynous and 

 usually have several carpels. The Leguminosae have mostly irregular 

 flowers that are hypogynous or somewhat perigynous and have a single 

 carpel. 



Geraniales. This large order of herbs and woody plants, containing 

 about 9,000 species, is broken up into 20 families. Half of the species 

 belong to the Euphorbiaceae, of which the largest genus is Euphorbia. 

 Some familiar genera belonging to other families are Geranium, Pelargo- 

 nium, Oxalis, Linum, and Citrus. The flowers are regular or irregular, 

 hypogynous, syncarpous, and pentamerous throughout or often reduced. 

 In the Euphorbiaceae the flowers are imperfect and apetalous, while in 

 some members they are naked. The stamens of the Geraniales are rarely 

 more than twice as many as the petals and usually equal to them in num- 

 ber. This is the first definitely cyclic and isocarpic order in the Archi- 

 chlamydeae, but it shows a tendency to reduce the number of carpels. 



Sapindales. The Sapindales, with about 3,000 species, most of which 

 are woody, are separated into 21 families. Here belong the sumacs 

 (Rhus), hollies (Ilex), maples (Acer), buckeyes (Aesculus), balsams 



