106 THE FERTILISATION OF FLOWERS. [PART IIT, 
Pringlea antiscorbutica, Hook., grows on the tempestuous shores 
of Kerguelen’s Island, where winged insects cannot exist, because at 
every flight they run the risk of being drowned. Under these 
circumstances the plant has become modified for fertilisation by 
the wind, acquiring exserted anthers and long filiform stigmatic 
papillz. It still retains traces of its descent from entomophilous 
ancestors ; for while on the great part of the island it is devoid ot 
petals, it occurs abundantly in sheltered places with petals. On 
the same raceme some flowers may possess only a single petal, 
others two, three, or four; and the petals, though usually of a 
pale greenish colour, are occisignilly adorned with Bec (216, 
372). 
Fig. 33.—Kernera saxatilis, Rich. 
A.—Flower, viewed from above. 
B.—Ditto, from the side, after removal of two petals (x 7), k, short stamens. 
33. TEESDALIA NUDICAULIS, R. Br.—The structure of this 
flower, whose longest petals are only two mm. long, differs 
remarkably from our other native Crucifers. 
During the period of flowering, the flowers are aggregated into 
a flat surface, whose outermost petals are larger than the others, as 
in the case of Umbellifers. But in 7eesdalia, as flowering progresses, 
the axis lengthens and draws out the flat surface into a raceme, 
so that each flower comes to stand at the edge in its turn. So 
it is not only certain flowers that stand from the beginning at 
the edge, which have the corolla specially developed on the outer 
side (as in many Umbelliferw and Composite), and thus become 
symmetrical about a single axis (zygomorphic) ; but all the flowers 
have their outer petals specially developed, and thus acquire a 
zygomorphic symmetry. 
Each flower has a superior (s), an inferior (s’), and two lateral 
sepals (s”), which help to render the flower conspicuous by white 
tips and a white median ridge; but conspicuousness is chiefly 
