THE DICOTYLEDONES 



1725 



flowers. The most widespread genus is Stellaria, which includes such 

 common plants as the Stitchworts and the Chickweeds. Among others we 

 may mention Lychnis (Fig. 1600) (Campion), Spergularia (Spurrey), 

 Arenaria (Sandwort), Sagina (Pearlwort), Cerastium (Chickweed), Silene 

 (Catchfly) and Dianthus (Pink). 



Among cultivated plants we may mention particularly the genus 

 Dianthus, from which the Pinks, Carnations, Picotees and Sweet William 

 of our gardens have been derived. Various species of Gypsophila and 

 Lychnis are also grown extensively for their flowers. The plants are mostly 

 herbaceous with swollen stem nodes and opposite, simple, entire and 

 usually exstipulate leaves. Many are annuals, but others form woody 



Fig. 1600. — Melandriiim (Lychnis) dioi- 

 ciim. Flower. 



Fig. 1 60 1. — Floral diayrani of 

 Stellaria media. Car\ophylla- 

 ceae. All the antipetalous 

 stamens are mifising and two 

 of the antisepalous stamens. 

 There is great meristic 

 \ariation in the famih', the 

 number of staniens varying 

 from I to ID and of carpels 

 from I to 5. 



perennial growths near the ground or, in the warmer parts of the world, 

 form small shrubs. The development of the leaves is unusual. At each node 

 one leaf develops earlier than the other. This bears in its axil a more 

 vigorous bud than on the other side and frequently it is only this bud which 

 later develops. 



The inflorescence is cymose and is usually a dichasium. Occasionally 

 as in Githago segetum (Corn Cockle) the flowers are solitary. 



The flowers (Fig. 1601) are actinomorphic, usually hermaphrodite 

 and pentamerous, but occasionally unisexual or tetramerous. 



The calyx is composed of five, rarely four, sepals which are either 

 free or united together into a tube. They are imbricated, with mem- 

 branous margins. 



The corolla is made up of five, rarely four, petals or the petals may be 

 absent. Unlike the sepals, the petals are never united together. 



The androecium consists of ten, occasionally eight or fewer stamens 



