BUCKTHORN 269 



The $ flower has an inferior ovary, sunk in the 

 calyx-tube, which ends above in 4 small teeth ; petals as 

 before, stamens none. Ovary 1 -chambered, crowned by an 

 epigynous disc, and a short thick style with an oblique 

 and slightly bifid peltate stigma. Pollen ellipsoid, drying 

 to tetrahedra, with 3 furrows. 



ft Ovary superior, the 4 whitish petals very 

 minute. Flowers in axillary tufts, yellowish- 

 green. Fruit a black drupe. Spinose shrub. 



Rhamnus Catharticus, L. The Buckthorn. Often has 

 polygamous flowers, though they are usually dioecious, 

 and will then come here : its alliances are with Rhamnus 

 Frangula. It is rather like Prunus spinosa in habit. 

 See p. 310. 



The small, yellowish-green flowers are in axillary 

 bunches (really cymose, but may be solitary) at the 

 bases of the young shoots : they are fragrant, entomo- 

 philous, and dioecious. Pedicels longer than the calyx. 

 Floral formula K 4 C\ A 4 G 4. Sepals spreading cross- 

 wise, secreting honey; lanceolate, as long as the calyx- 

 tube ; petals very minute or even obsolete, and the short 

 stamens when present superposed on them. Ovary sunk 

 in the cup of the calyx and ripening to a black drupe 

 about the size of a pea. Most of the flowers on a plant 

 have either no stamens or no ovary, or mere rudiments of 

 one or the other; but occasionally some of the flowers 

 have both stamens and pistil, and are polygamous. Pollen 

 white, rounded elliptic to ovoid, about 31 x 25 //,. 



[The Holly is physiologically sub-dioecious, but the 

 stamens in the $ flowers are so apparently perfect and 

 large that they appear c : moreover truly < flowers do 

 occur sometimes. See p. 288.] 



