DICOTYLEDONES : POLYPETAL^ : CALYCIFLORiE. 



639 



usually two, diverging above (Fig. 335 D) : inflorescence of racemose cymes : 

 fruit a capsule : leaves alternate. 



The British genera are Saxifraga and Chrysosplenium :— Saxifraga has an 

 oblique bilocular ovary, and the flower is consequently obliquely zygomorphic 

 (Fig. 324 C) ; the receptacle invests the lower connate portion of the ovary : 

 many species occur in mountainous districts, and in several of them there is a 

 deposit of carbonate of lime on the margins of the leaves (see Fig. 100, p. 139) ; 

 only a few species, such as S. tridactylites and granulata, occur in the plains : 

 Chrysosplenium, the Golden Saxifrage, has a tetramerous flower destitute of a 

 corolla ; they are small plants, somewhat resembling a Euphorbia, occurring in 

 damp places. Among the more familiar cultivated genera are Astilbe (Hoteia), 

 Rodgersia, Bergenia (Fig. 439), Tiarella, Heuchera, etc. 



Tribe 2. Paniassiece. Flowers perigynous, often actinomorphic ; the five 

 stamens opposite to the petals are transformed into glandular staminodes ; 



FiG. 439.— Longitudinal section of the 

 ovary of Bergenia ; g style ; n stigmata ; 

 p placentae (mag.)- (After Sachs.) 



Fig. 440.— Floral diagram of Parnassia ; 

 but the whorl of antipetalons staminode-s 

 should be represented as external to the 

 whorl of stamens. 



petals with imbricate aestivation : ovary 4-5-merous, unilocular : fruit a loculi- 

 cidal capsule : leaves alternate, 



Parnassia palustris, Grass of Parnassus, has a whorl of radical leaves, and 

 terminal and lateral peduncles each bearing a single flower and adnate to a 

 bracteole : it is frequently found in damp localities. 



Tribe 3. Hydrangece. Flowers epigynous, actinomorphic, obdiplostemonous : 

 petals with valvate testivation : carpels 3-5 : shrubs with opposite leaves. 



Hydrangea hortemis is a well-known garden plant. The inflorescence is an 

 umbellate panicle, the marginal flowers of which (in cultivated plants all of 

 them) are sterile, having a very much enlarged calyx, and either no stamens or 

 only the whorl of stamens opposite to the sepals. 



Tribe 4. PhiladelphetP. Flowers epigynous, actinomorphic, 4-5-merous : 

 stamens in two whorls but not obdiplostemonous, or indefinite : petals with 

 various testivation : fruit a capsule : shrubs with opposite leaves. 



Philadelphm coronarius (called Syringa or Mock Orange) has sweetly-scented 

 tetramerous flowers. Deutzia scabra, crenata, and others are cultivated. 

 V. S. B. T T 



