1 100 A TEXTBOOK OF THEORETICAL BOTANY 



flowers of the Orchidaceae and Lobeliaceae, though in the former case, there 



being no pedicel, it is the sessile inferior ovary which is twisted through i8o°. 



Resupination is a puzzling character, which appears here and there in a 



number of families, but only in insect- 

 pollinated flowers. In some cases, it 

 provides a better landing ground for 

 the insect visitor, but this is not 

 invariable. Its utility may vary in differ- 

 ent cases, but some relation to polli- 

 nation conditions is indicated. 



Zygomorphy is most general in 

 lateral flowers; terminal zygomorphic 

 flowers are rare. It is therefore gener- 

 ally associated wath racemose inflores- 

 cences. Occasionally terminal flowers 

 may appear in an inflorescence of 

 zygomorphic flowers, but they are then 

 anomalously actinomorphic, due to the 

 formation of compensating irregular- 

 ities all round the flower, which is 

 also sometimes monstrous. The abnor- 

 mality is hereditary in certain strains, 

 as in the well-known " Gloxinia- 

 flowered " Foxglove {Digitalis) (Fig. 

 1070). The condition is called peloria 

 (see p. 1 1 56). 



Comparison of flowers in respect of 

 their vertical, as distinct from their 

 horizontal symmetry, shows that this 

 frequently varies according to the 

 form of the floral receptacle (see 

 p. 1 103), but that variation in other 

 respects is decidedly rare. The normal 

 seriation of parts, for example, is highly 

 constant. In Malus spectahilis carpels 

 sometimes arise among the stamens, 

 but this is an inconstant anomaly. In 

 TrigJochin maritimiim, on the other 

 hand, it is surprising to find, as a nor- 

 mal feature, a whorl of perianth mem- 

 bers apparently intervening between 

 the two whorls of stamens (Fig. 1071). 

 A displacement of the outer staminal 



Fig. 1070. — Di'jitalis piirpuiea. Inflores- , , ^ -4. if „„ „., ^-^r^1or-.o+;/-.r. 



cence with large terminal, pelor.c whorl Suggests itself as an explanation, 

 flower, which is actinomorphic, similar to that taking place, according 

 ^phl^ ('S'^wZ*" '''"" '» ^-y^^' in ohliplostemonous flowers. 



