VIVIPAROUS AND PROLIFEROUS FERNS. 



91 



distinct sorts of fronds, the sterile ones being dark green, prostrate, and 

 proliferous, and the fertile ones much longer, narrower, erect, but not 

 proliferous. Again, there is the West Indian Aspidium (Pohjstichum) vivi- 

 parum, an evergreen species with erect caudex, from which glossy dark 

 green fronds, of great substance, and of a somewhat prickly nature, are 

 produced with great regularity, forming a very handsome plant, which 

 seldom attains more than 20in. in height. 



Of Aspleniums there are numerous sorts whose fronds are provided with 

 a solitary and terminal bulbil. Most conspicuous among these are the delicate 

 little Australian A. flabellifolium, with its pretty fan-shaped pinnae, the 

 reddish-brown sori covering the under side ; A. alatum ; A. attenuatum ; the 

 rare and pretty A. brachypteron, from Fernando Po, where it grows at a high 

 elevation on the Cameroon Mountains ; A. lunulatum (erectum) Femandesianum 

 and A. I. tenellum ; and the attractive little A. obttisilobu?n, a pretty, dwarf, 

 trailing species from the Fiji Islands, with pinnate fronds from 4in. to 6in. 

 long, proliferous at their apex, and making a dense, compact mass of 

 foliage, &c. Then there are the curious Pteris (Doryopteris) palmata, 

 P. pedata, P. sagittifolia, and the equally strange Hemionitis cordata, in 

 all of which the bulbil, instead of being terminal, is situated at the base 

 of the limb of the fronds ; and various other kinds partaking of the 

 same character. 



Perhaps the most interesting of all in this group is Trichomanes 

 pinnatum (floribundum) , the only Proliferous Filmy Fern at present known. 

 It is a native of the West Indies, and its simply-pinnate fronds, from 

 lft. to l^ft. long, are exquisitely transparent ; the pinnae are beautifully 

 fringed on their edges, and the fronds are attenuated, rooting at their 

 extremity. Unfortunately, it is essentially a warm-house species, and, not- 

 withstanding the numerous attempts which have been made, it has constantly 

 refused to thrive under the cool treatment so suitable to most other kinds. 



Group IV. 



When we come to the fourth group— exclusively composed of Ferns which 

 have the base of their stalks provided with either stolons, roots, or scales, of a 

 proliferous nature, each of these bearing one or more latent buds or bulbils, 



