Classification of Plants 



311 



Inflorescence a raceme, panicle, or spike, apparently cymose 

 in Dalbergia. The order is divided into three groups or sub- 

 orders. 



Mimoseae. — Flowers regular. Corolla valvate. Stamens many 

 or 10. 



Caesalpineae. — Flowers zygomorphic or nearly regular, back petal 

 folded within the side petals, which are overlapped by the front petals. 

 Stamens 10 or fewer. 



Papilionaceae. — Flowers irregular, back petal (standard) folding over 

 the side petals (wings or alae). The side petals overlap the two front 

 petals, which join to form the keel. Stamens 10. 



In some flowers of this group the stamens and pistil are 

 held in the keel, and are released with an explosion, as in 

 Indigofera, so that only one visit of the bee is invited. In the 

 Sweet Pea a brush on the style sweeps the pollen out of the 

 keel. The flowers are usually self-pollinated. In the Bean 

 and Snail Creeper the stigma is forced out when the bee presses 

 down upon the wings, and returns when it flies away, so that 

 the bee is invited repeatedly. 



Fig. 284. — Floral diagrams of Leguminosae, showing folding of sepals and 

 petals in I. Mimosece ; II. CcesalpinecB ; III. Papilionacece. 



Sub-tribe Mimose^. 



A. Stamens indefinit ; pollen collected in masses. 



B. Stamens free. 



Acacia. — The minute flowers are clustered in golden 

 heads or spikes. They are delightfully fragrant. The sepals 

 form a short tube. 



Trees with twice-pinnate leaves, except in the Australian wattles, 

 which often develop the blade only in the first few leaves ; the petiole 

 then becomes flattened (Phyllode) with the edge turned toward the sun. 



