264 BRITISH FLOWERING PLANTS chap. 



The corolla is small, and the red colour is due to 

 the calyx, which has four small bracts at the base. 

 The appendages of the anthers are covered with rough 

 hairs. The leaves are glabrous, and somewhat concave 

 below. It is a Northern and Alpine species, especially 

 adapted to resist cold (see p. 27). The leaves are, as a 

 rule, closely appressed to the stem, but in shady places 

 diverge from it so as to receive more light. 



Pyrola (Wintergreen) 



Low herbs, sometimes rather woody ; some with, 

 others without, honey. We have five species. One, 

 P. unijlora, has a single flower, the others several. P. 

 seeunda has small flowers in a one-sided raceme, and 

 pointed leaves. In P. rotundifolia the style is much 

 longer than the corolla and curved ; in P. intermedia 

 it is longer and straight ; in P. minor it is not longer 

 than the corolla. The pollen grains remain coherent in 

 fours. This fact, which we have noted in other species, 

 is simply the persistence of an earlier stage of develop- 

 ment. The pollen grains are formed by division of a 

 mother cell into four as a result of successive bipartition. 

 In so-called powdery pollen the separation of the daughter 

 pollen grains is complete, but not infrequently they 

 remain aggregated in the original tetrad. 



P. seeunda. ^ — The flowers are protogynous, and 

 crowded on a one-sided spike ; the petals are greenish 

 white. This species may be taken as typical of the 

 genus. Honey is secreted at the base of the corolla. 

 The anthers open near the base, which, however, is 

 brought upwards by a curvature of the stamens. The 

 anthers are kept in this position, with the pore 

 upwards, by the petals, but when an insect pushes 

 into the flower and presses back one of the petals, the 

 anther at once drops down, and some of the pollen 

 falls out. 



P. uniflora. — The flowers are large, but honeyless ; 

 the general arrangement is as in P. seeunda. The 



