154 GERANIACE^ 



consider it to be a natural secretion from the leaf of this and other trees. 

 Pliny gravely hesitated whether he should regard this exudation as the 

 " sweat of the heavens, the saliva of the stars, or a liquid produced by the 

 purgation of the air." There is no doubt that, though this stickiness may 

 be at times due to the secretions of aphides, it is in most cases attributable 

 to the vital energy of the tree itself, analogous to the "gumming" of plum 

 and other trees, and consequent ujDon the over-production of certain sub- 

 stances in the tissues. This honey-dew is sweet as well as sticky, containing 

 both mannite and cane-sugar, which accounts for its attractive quality as 

 concerning insects. But it also affords a suitable nidus for the germination 

 of the spores of various fungi, which in turn draw nutriment from the leaf- 

 tissues, and so set up unhealthy conditions resulting in the premature fall of 

 the leaf, without, however, entailing any real injury to the tree. 



Very frequently, in autumn, the foliage of the Sycamore is more or less 

 disfigured by a black fungus, which gives to the leaves the appearance of 

 having had large drops of ink scattered upon them. In some seasons these 

 spots are very abundant, and in one year the author saw a row of Sycamores 

 in which almost every leaf was thus disfigured, so as to attract the notice of 

 those who rarely observed plants. This fungus is the Uncinida hicornis, and 

 when observed with a powerful microscope it is seen to be a curled tubercle, 

 with a rugged border. The leaves so affected fall off at the first frost, and 

 these spots then gradually corrode their entire substance. 



The Sycamore-tree is never more attractive than in the early spring, 

 when the young, tender, green foliage is shooting forth, and when the small 

 pink scales, which at first envelop the handsome lobed leaf, are just being 

 scattered around the tree by every gust of wind. When autumn is on its 

 way, the more sober red of the gradually ripening winged seed-vessels, as 

 well as the varied hues of the foliage, are also very ornamental among the 

 deepening tints of the wood. Cowper described it as — 



' ' The Sycamore, capricious in attire, 

 Now green, now tawny, and ere autumn yet 

 Has changed the wood, in scarlet honours bright." 



Order XX. GERANIACE^E— GERANIUM TRIBE. 



Sepals 5, not falling, ribbed, overlapping when ii\ bud ; petals 5, clawed, 

 twisted while in bud ; stamens 10, often alternately imperfect, usually united 

 by their filaments ; ovary of 5 carpels, placed round a long awl-shaped beak ; 

 styles 5, united to the beak ; stigmas 5 ; fruit beaked, separating into 

 5 capsules at the base of the beak, and terminating in a long awn, which 

 finally curls up, bearing with it the capsule. This is a large Order, composed 

 chiefly of herbaceous plants, but comprehending also a few shrubs. The 

 genera are distributed over various parts of the world, a great number of 

 them being found at the Cape of Good Hope. These are chiefly the Pelar- 

 goniums, which are the plants usually called Geraniums, some of which are 

 to be found in most gardens, and are the commonest of window plants. 

 The genera Erodium and Geranium are mostly natives of Europe, North 

 America, and Nortliern Asia. A slight degree of astringency and acidity is 



