THE LIFE-HISTOEY OF PLANTS. 



187 



Brownea. — Named in honour of Patrick Browne, 

 an English physician who wrote and published an 

 illustrated history of Jamaica upwards of one hun- 

 dred and twenty years ago. The plants comprising 

 this genus belong to the order Legtn)n>ws(e, but 

 to that division which have regular, not Pea-shaped, 

 flowers. 



Browneas form small bushy trees, and thrive best 

 when planted out in the stove, or in good-sized 

 tubs, where they form noble ornaments ; the leaves 

 are large and pinnate, and their globose heads of 

 flowers are not unlike the Rhododendrons at the 

 first glance. These plants thrive best in a mixtvu-e 

 of about two parts of loam, one of peat, one of leaf- 

 mould, and a little sharp sand ; they enjoy strong 

 heat and an abundant supply of water, and shading 

 from the direct rays of the midday sun. In winter, 

 over-watering must however be avoided. Cuttings 

 for propagation should be taken from ripened wood, 

 and struck in sand under glass in a moist atmo- 

 sphere. 



B. Ariza. — This species attains a height of thirty 

 or fortj" feet, and is by far the largest in the genus ; 

 leaves pinnate, leaflets oblong-lanceolate, and deep 

 green ; the flowers are deep red, produced in large 

 dense heads. Summer months. Bogota. 



B. coccinea. — Height six to eight feet or more ; 

 they are all similar in appearance ; the globose heads 

 of flowers are brilliant scarlet. Summer months. 

 West Indies. 



B. (jrandiceps. — This is the " Rosa del Monte " of 

 the Venezuelans ; it attains a height of six to ten 

 feet, and, as its name implies, produces very large 

 heads of bloom, which are some eight to ten inches 

 across ; flowers deep rosy-pink. Summer months. 

 A-'enezuela and Caraccas. 



Burcliellia. — A small family of Cinchonaeece, 

 named in compliment to the late Mr. Burchell, who 

 travelled in South Africa, and made extensive col- 

 lections of specimens in the animal as well as the 

 vegetable kingdom. Pot in peat and loam in equal 

 parts, with a little sand, and drain well. Interme- 

 diate House. 



B. capensis. — This plant is called the " Buffel," or 

 "Buffalo Horn," at the Cape, on account of the 

 hardness of the wood of its stems ; it seldom exceeds 

 six feet in height, and is much branched; these 

 branches are clothed with opposite leaves, which are 

 somewhat oblong, slightly hairy and deep green ; 

 the flowers are tubular, borne in closely -packed 

 heads, rich scarlet in colour. Spring months. South 

 Africa. 



B. parvijlora. — Resembles the preceding, but is 

 neither so large nor so free-flowering as that species. 

 Spring months. South Africa. 



THE LIFE-HISTOEY OF PLANTS. 



Bt Dk. Maxwell T. Masteks, F.E.S. 



FERTILISATION. 



FROM what has been previousl}- said, it is clear 

 that the pollen has to be got to the stigma in some 

 way or other, and our present object is to see how 

 this is effected. From the frequent juxta -position 

 of the anthers to the stigma, and from various ar- 

 rangements which seem to bring about, and 

 really do bring about, the contact of the pollen 

 with the stigma, it was naturally thought that 

 the stigma or germ of any given flower was 

 necessarily fertilised by the pollen of the same 

 flower; but though this " close fertilisation" does 

 occur, and in some cases is inevitable, yet "cross- 

 fertilisation," or that by which the germ of one 

 flower is impregnated by the pollen of another 

 flower, is more common and, in the long run, accord- 

 ing to the experiments of Knight and Darwin, more 

 advantageous to the plant in the sense of producing 

 a succession of numerous and more robust healthy 

 seedlings. Mention has already been made of the very 

 frequent cases where the pollen of any given flower is 

 practically ineffective from the fact that the stigma 

 of that flower is not ripe for its reception, or, on the 

 contrary, the stigma may be ripe and the anthers 

 ■unexpanded. Mention has also been made of 

 "dioecious" plants like the Willow, in which the 

 sexes are on different plants. In such cases close 

 fertilisation is impossible, and cross-fertilisation in- 

 e^itable. The exti^emely varied forms of flowers 

 have often reference to these peculiarities ; the ar- 

 rangement, position, and mechanism of the flower 

 being such as necessarily to prevent close fertilisa- 

 tion and to promote cross-fertilisation. 



It is easy to conceive of several ways in which 

 pollen might be conveyed from one flower to another ; 

 but, practically, we need here only consider two — the 

 impulsion of the wind and the porterage of insects. 

 Flowers that are fertilised by means of wind-wafted 

 pollen have usually relatively inconspicuous flowers, 

 the floral construction is of the simplest, generally- 

 devoid of brilHant colour or potent odour. The 

 pollen itself is relatively small, smooth, sometimes 

 proA-ided with wing-like expansions as in Pines, and 

 generally produced in large quantities. 



Insect Agency. — On the other hand, insect- 

 borne pollen is usually produced in flowers of more 

 or less complicated construction, of brilliant colour, 

 and powerful odour. The pollen of such flowers 

 is frequently provided with ridges, spines, or other 

 projections well adapted to adhere to the legs or 

 backs of insects. Here then we get the clue to the 

 reason of the bright colours, the varied and often 



