AESCULIN&. 



441 



symmetry (through the 4fch sepal, Fig. 471); there are 5 sepals, 5 free 

 petals, of which the one lying between S 3 and S 5 is the smallest 

 (see Fig. 471) and may be absent ; stamens 7 (5 + 2), three being 

 suppressed ; gyncecenm simple, 3-carpellary and 3-locular, with 

 single style ; of the two ovules one is ascending, the other descend- 

 ing (Fig. 472). The fruit is a 3-valvate, sometimes spiny, capsule, 

 with loculicidal dehiscence, the seed having a large hilum, a 

 curved embryo without endosperm and united cotyledons (the 

 radicle lies in a fold of the testa, Fig. 473). JR. Tiippocastanum 

 (Greece, Asia), introduced into cultivation about 300 years ago ; 

 the majority of the other species, e.g. 2E. pavia, etc., several of 

 which are frequently cultivated in gardens, are from N. America. 

 The flower of the Horse-Chestnut is adapted for bees, whose abdomen touches 

 the anthers or style when visiting the flower. The flowers are protogyuous. 



The other Sapindacefe have most frequently 4 sepals, 8 stamens, various 

 fruits (septicidal capsule, nuts with or without wings, schizocarp), etc. Ser- 

 jania, Cardiospermum, Sapindug, Koelreutiria, etc. (about 118 genera, 970 

 species). The seeds of Paullinia sorbilis contain caffeine, and are used as 

 "Pasta guarana," in the North Western Brazils in the manufacture of a 

 common drink. Nephelium (or Euphoria) litchi (with edible aril), and other 

 species, from Asia. 



Order 4. Aceraceae. This order is so closely allied to the 

 Sapindacea?, that some authorities have classed it with them. 

 The main difference is 

 in the regularity of the 

 flowers, and the 2-mer- 

 ous gynoeceum (in ab- 

 normal cases several 

 carpels occur). They 

 are trees, and, like the 

 Horse- Chestnuts, have 

 opposite leaves without 

 stipules ; in Acer the 

 leaves are palminerved, 

 but imparipinnate in 

 Negundo, a plant fre- 

 quently cultivated in 

 gardens. The flowers 

 are often unisexual, polygamous (some species have $-,<?- and 

 ? -flowers); sepals 5, petals 5 free, stamens 8 (that is, 5 + 5, but 

 the two median ones are absent) inside a large disc. Fruit a 

 samara (schizocarp) with 2 winged, nut-like fruitlets (Fig. 474). 



FIG. 474. Samara of Acer platanoides. 



