s TJie President's Address. By Lord Avebury. 149 



are lowly herbs with handsome foliage, gorgeously variegated in the 

 case of Caladium and other species, while others, like Diejfen- 

 bachia, are richly blotched with cream or yellow markings. Some 

 are aquatics, growing in shallow water, like Orontium, Calla, and 

 Acorus, while Pistia stratiotes is a floating herb. Some of the purely 

 herbaceous species attain a gigantic size, as in the case of Amorpho- 

 phallus, but particularly Conophallus titanus, which produces a 

 single leaf, with a stalk 6-7 ft. high and a blade 45 ft. in circum- 

 ference. The spathe measures 3 ft. in diameter, making one of the 

 largest known flowers, popularly so-called. 



In temperate regions the plants are chiefly dwarf herbs, and to 

 this class belong the land plants, Arum maculat urn and A. italicn un, 

 as well as the aquatic Acorus, or Sweet Flag. The highly coloured 

 fruits of Arum are probably adapted for dissemination by birds, 

 but Acorus Calamus, with its curious, but inconspicuous and un- 

 attractive, conical mass of fruits, must be generally dispersed by 

 water, carrying away the fruits or pieces of the plant. The seeds 

 do not often come to maturity in this country, but when that 

 happens, the pulpy baccate fruits may induce aquatic birds to carry 

 them away. 



The curious flowers of the common Arum maculatum Linn. 

 (Lords and Ladies) are crowded together in four series on a central 

 axis, or spadix, inclosed by a large spathe in direct correlation to 

 the method by which they are fertilised. Near the base of the 

 spadix is a group of ovaries, without a protecting perianth, as this 

 is rendered unnecessary by the presence of the spathe. Above this 

 is a group of hairs, representing imperfect ovaries. Next comes 

 a dense cylindrical mass of anthers, likewise without a perianth, 

 and above them is another group of hairs, representing imperfect 

 anthers. The crowding together of the flowers in this fashion 

 would tend to reduce the size of the ovaries and their contained 

 ovules or seeds. This may account for the presence of infertile 

 ovaries and anthers, so that the energies of the plant are devoted to 

 the production of only a few ovules and still fewer seeds. 



In this case, nothing would at first sight seem easier or more 

 natural than that the pollen from the anthers should fall on, and 

 fertilise, the pistils. This, however, is not what occurs. The 

 stigmas mature before the anthers, and by the time the pollen is 

 shed, have become incapable of fertilisation. It is impossible, 

 therefore, that the plant should fertilise itself. Nor can the pollen 

 be carried by the wind. When it is shed, it drops to the bottom of 

 the tube, where it is so effectually sheltered that nothing short of a 

 hurricane could dislodge it ; and although Arum is common enough, 

 still the chances against any of the pollen so dislodged being blown 

 into the tube of another plant would be immense. 



As, however, in Aristolocliia , so also in Arum, small flies, espe- 

 cially those belonging to the genus Psychoda, attracted by the 



