ON FERNS. 



5 2 7 



some of the gigantic Tree-Ferns attain some 50ft. in height, others 

 seldom exceed a few inches ; and, as regards the fronds themselves, 

 although in the case of certain Polypodiums, Trichomanes, and 

 others, these organs are only an inch or even less, in others they 

 reach fully 15ft. in length. Again, some kinds affect a bushy and 

 symmetrical form, whereas others are provided with rhizomes or 

 stems which naturally grow many yards in length, twining round 

 other plants or climbing to the top of tall trees. 



Although in the majority of cases their foliage is of a uniform 

 green colour, yet either in the course of development, or when fully 

 matured, their 

 fronds, in some 

 cases entire, and 

 in others more 

 or less finely 

 divided, exhibit a 

 most extensive 

 variety of shades, 

 ranging from the 

 dark colour pecu- 

 liar to the Hard 

 Fern, Blechnum 

 Spicant, or to the 

 Soft Prickly Shield 

 Fern, Polystichum 

 annulare, to the 

 soft pea-green tint 

 of our common 

 Oak Fern, Poly po- 

 dium Dryopteris, 

 or the lovely 

 Adiantum trapezi- 

 forme (Fig. 332). 

 Others, like the 

 common Poly- 

 podium aureum, a 

 deservedly popu- 

 lar, strong-growing 

 kind, or the small, 

 dwarf - growing 

 P. glaucophyllum, 

 retain all through 



their existence a most pleasing bluish tint which forcibly 

 reminds one of the foliage of Eucalyptus globulus. Others, 

 again, although quite green when mature are, during their 

 development, of most brilliant bronzy or metallic tints. This 

 peculiar character is particularly noticeable among the Adiantums, 

 some of which, like A. Veitchii, rubellum, tinctum, macrophyllum, 



Fig. 332. — Adiantum trapeziforme. 



