APPENDIX A 



529 



beyond the curved stamens, thus there is a probability of cross-pollination 

 from visits from humble-bees, but the flower is not highly specialised. 



(37) The Potato (Solanum tuberosum, L.) is an herbaceous plant that 

 reproduces itself by tubers (Fig. 138, p. 185). But it commonly flowers also 

 in cymose inflorescences, which are without bracts. The flowers of the 

 cultivated varieties are apt to show abnormalities. The normal structure is 



FIG. 435. 



Solanum tuberosum. I. flower. IT. pistil, and persistent calyx. III. stamen with 

 porous clehiscence. IV. seed in median section. V. floral diagram. 



like Atropa in number and arrangement of parts. But the corolla is wheel - 

 shaped, and expanded in a vertical plane, while the five projecting stamens 

 open by terminal pores (Fig. 435). The stigma projects beyond them. 

 There is no honey-secretion. The native habitat is South America. The 

 arrangement of the flower might lead to crossing if the suitable insects 

 were present, but here insects rarely visit the flowers. Self-pollination is 

 possible, and fruit is often set. The fruit is a berry. 



ORDER: PERSONATAE. 

 Family : SCROPHULARIACEAE. Examples : FIGWORT, SPEEDWELL. 



(38) The Figwort (Scrophularia nodosa, L.) is a common plant of moist 

 soil, with upright four-angled stems bearing decussate leaves, and terminating 

 in lax cymose panicles of tawny purplish flowers. They are zygomorphic, 

 and strongly protogynous (Fig. 436) . Each flower consists of : 



Calyx, sepals 5, slightly gamosepalous, inferior. The odd sepal is posterior. 



Corolla, petals 5, gamopetalous, inferior ; two-lipped. 



Androecium, stamens 4, epipetalous ; the fifth posterior stamen represented 

 by a prominent staminode below the upper lip. 



Gynoecium, carpels 2, syncarpous, superior, antero-posterior ; style elongated 

 stigma capitate. Ovary bilocular, with numerous ovules on an enlarged axile 

 placenta. A yellow honey-disc surrounds the base of the ovary. Fruit a 

 dry capsule, which splits septicidally, and liberates the numerous albuminous 

 seeds, with straight embryos. 



