1 68 Plants and their Ways in South Africa 



indicate the way to refreshments. A transparency is of little 

 value unless a light shines through it. Flowers that open in a 

 shaded room have a much lighter colour. The pigment that 

 gives the flowers their brilliancy is often concentrated in 

 bright patches on the three lower parts of the perianth, where 

 irregular flowers of this order are usually marked. 



Are the flowers all turned in the same direction on the 

 stem? If they turn toward the light the transparency would 

 lose its effect. Do you find them turned toward the light or 

 away from it ? At which end of the flower-stalk does the 

 visiting insect begin when in quest of honey? Do different 

 insects have the same habit ? Maybe you can already answer 

 some of the questions. If you cannot, 

 it will pay you to watch with us. 



Although so many attract insects by 

 colour or odour, some flowers are self- 

 fertilized. The violet has inconspicuous 

 flowers late in the season. They never 

 open, and so have to be self-fertilized. 

 Branches bearing self- fertilized (cleisto- 

 gamous) flowers of the blue Commelina 

 (C. Benghalensis, Linn.) bore underground 

 where the seeds ripen. Some species of 

 Oxalis and Stapelia also have closed 

 flowers after the others have withered. 

 In early times such extravagance as bril- 

 liant colour, 1 honey, and choice perfume 

 was not indulged in by plants ages ago 

 when the wind was the only method of 

 transporting pollen. An abundance of 

 pollen had to be provided in those days, 

 as the wind is a wasteful messenger. The 

 conifers doubtless shed their pollen to the 

 breeze before the hum of flies and bees had been heard. Grasses 

 have kept the old-time habit. Or may it be one they have ac- 

 quired ? Their long filaments hang out the swinging anthers to 



1 While we associate colour of flowers with insects' visits, colour may 

 be due to chemical changes in the plant without reference to insects. 



FIG. 165. The swing- 

 ing anthers of grasses 

 scatter their pollen in 

 the wind, which the 

 feathery stigma 

 catches. (From 

 Thome and Bennett's 

 "Structural and 

 Physiological Bo- 

 tany".) 



