302 BRITISH FLOWERING PLANTS chai-. 



Orobanche (Broomrape) 



We have seven species. The embryo shows no 

 differentiation into root and stem, and has no cotyle- 

 dons. It is a delicate simple filament, and the end 

 which corresponds to the shoot remains in the seed. 

 The other end works its way down into the earth in a 

 spiral line. If it does not meet with a suitable host it 

 soon dies, and indeed the vast majority perish. The 

 seeds, however, are very numerous. If the rootlet 

 finds a suitable host it adheres to it and thickens, the 

 upper part perishing. The thickened part drives pegs 

 into the root to which it has attached itself, sucks out 

 sap, and forms a bud which grows into a short, thick, 

 strong stem. The plant also throws out rootlets, which 

 probably derive a certain amount of nourishment from 

 the soil. 



0. caryophyllacea. — The flowers are homogamous ; 

 sweet-smelling, and with nectar. The corolla-tube is 

 somewhat bent, gradually widening to the middle ; the 

 underlip is trifid and thrown into folds, which so much 

 diminish the width of the tube that insects are almost 

 certain to touch the anthers and stigma. The latter 

 projects beyond the stamens. The four anthers are 

 grown together at the sides, and each chamber is pro- 

 vided with a long stiff horn directed downwards. If 

 these are shaken by an insect the dry pulverulent pollen 

 falls on its head or proboscis. The flower does not 

 fertilise itself The plant is parasitic on species of 

 Galium, Eubus, etc. 



0. elatior. — The flowers are scentless and without 

 nectar. The stigma at first projects beyond the anthers, 

 which, however, gradually grow up to it, so that self- 

 fertilisation is possible. The stem is glandular-pubescent. 

 The plant, which is parasitic on Centaurea Scabiosa, is 

 rare, and found chiefly in the eastern counties. 



0. ramosa. — Pale straw colour. The arrangement 

 of the flower resembles that of O. elatior. According 

 to Kirchner and Warnstorf, it is slightly protogynous. 



