430 



HUTCHINSON'S POPULAR BOTANY 



above. No longer tucked away out of sight under the hood, the style will 

 have elongated and curved over, and the two forks of the stigma will 

 have opened wide, and be hanging just at the suitable height for picking 

 off the pollen from the bee's back. Clearly the old game of quintain, so 

 great a favourite with our forefathers, is not yet obsolete ! 



Irritability in the organs of flowers, particularly in the essential organs 

 (stamens and pistil), is almost always due to mechanical contrivances and 

 connected with cross-fertilization. Witness the irritable stamens of the 

 Common Barberry (Berberis vulyaria, fig. 502), which spring up and scatter 



their pollen on the head of the bee as it 



thrusts its proboscis into the nectar. Wit- 

 ness, too, the yet more remarkable stamens 

 of the American Laurel (Kalmia latifolia}. 

 a flower the pollination of which has been 

 very fully described by Professor Beal, of 

 Michigan. In this case the anthers are 

 forcibly held down in the saucer-shaped 

 corolla by means of little pockets, the 

 filaments being thus bent back and 

 transformed into so many springs. " It is 

 interesting to watch the operations of a 

 humble-bee upon the flowers," says another 

 American observer, Professor Asa Gray. 

 " The bee, remaining on the wing, circles 



Y for a moment over each flower, thrusting 



/vM^ty*'/ its proboscis all round the ovary at the 



V>M bottom ; in doing this it jostles and lets 



iPIL off the springs, and receives upon the under 



^V^"^ side of its body and its legs successive 



charges of pollen. Flying to another 

 blossom, it brings its pollen-dusted body 

 against the stigma, and commonly revolv- 

 ing on it as if on a pivot while it sucks 

 the nectar in the bottom of the flower-cap, 

 liberates the ten bowed stamens, and receives fresh charges of pollen 

 from that flower while fertilizing it with the preceding one." If flowers 

 of Kalmia are protected from insects (the experiment was tried by Mr. 

 Beal with coverings of fine gauze), they wither, drop off, and set no seed ; 

 the reason being that no stamen gets liberated of itself while fit for action 

 (figs. 503, 504). 



A curious method of clamping the pollen-masses (pollinia) of flowers to 

 the feet of insects is to be noticed in the Asclepiads, and has been dis- 

 tinguished as clip mechanism. In Asclepias cornuti, for example, the 

 connective of each pair of pollinia is a hard substance " capable of holding 



FIG. 533. SPOTTED OKCHIS. 



A flower, partly in section, visited by bee. In 



pushing its tongue down the spur, its head comes 



in contact with the pollen-masses and brings them 



away, as shown below. 



