PROTECTION OF POLLEN. 107- 



disappears, and in Australia the numerous Mimosese and Myrtacese and the 

 Proteacese, which constitute the principal part of the dense copses just referred 

 to, are accordingly destitute of any contrivance capable of acting as a protection 

 to the pollen. These plants preserve their rigid character even during the 

 flowering season; the filaments bearing the anthers project in large numbers far 

 beyond the small floral envelopes in the Acacias and in the innumerable species 

 of Callistemon, Melaleuca, Eucalyptus, Galothamnus, and Metrosideros, and the 

 styliform prolongations of the ovaries in Proteaceae, on the top of which the 

 pollen is deposited when set free from the anthers, spring up and stretch out 

 unprotected far beyond the restricted perianth. 



Flowers which inhabit a region where moisture is deposited from the atmo- 

 sphere in greatest quantity in the flowering season exhibit an entirely difierent 

 form. In the mountains of Central and Southern Europe, where this coincidence 

 occurs, the plants whilst in flower must be prepared for daily showers. In addition 

 every plant drips with dew in the early morning, and drops of water are deposited 

 on leaves and flowers in the course of the day by the mists as they roll by. 

 It must often happen that the pollen remains for days together hanging to 

 the opened anthers before it is carried away by bees or butterflies to the stigmas 

 of other flowers. Here if anywhere is an instance of the necessity of ample 

 shelter for the pollen. Examine the plants composing the smaller brushwood 

 of such a region, and you will find how great a contrast they afibrd to the plants 

 of the thickets of Australia. The flowers of the Heather (Calluna vulgaris), 

 and of the Bilberry, Bog Whortleberry, and Cowberry (Vaccinium Myrtillus, 

 V. uliginosum, V. Vitis-Idcea) have bell- or cup-shaped corollas which hang down 

 from curved stalks with the mouths of the flowers towards the earth, and so cover 

 the pollen-laden anthers. Similarly, we find the Alpine Khododendrons ("Alpine 

 Roses"), which clothe the mountain sides, with flowers inclined at a right angle 

 to the erect stalks so that the anthers are perfectly sheltered (cf. Plate X., after 

 a drawing by E. Heyn). 



All the many contrivances whereby pollen is directly protected from wet are 

 of the same nature as the above, the method of protection being by some such 

 roofing in or envelopment of the anthers. That these adaptations should exhibit 

 so much variety in detail in spite of the uniformity of their object is due to the 

 condition that the envelopment must itself not be carried too far. On no account 

 must the dissemination of the pollen or its transport by wind or insects to the 

 stigmas of other flowers be hindered; nay, the very same parts of a flower which 

 shelter the pollen from rain frequently have the additional function of assisting 

 the dispersion of the pollen when the rain is over. 



In the enumeration of arrangements for warding off injury to pollen from 



wetting, the various coverings and protections are described as equally effective 



^ for rain as for dew. But this, of course, is not for the same reason. A roof 



protects structures from"! rain by intercepting the drops, and from being bedewed 



since it diminishes radiation from the bodies beneath and thus keeps them at a 



