THE COMMON' PRICKLY SHIELD FERN. 



I>. aculeatum is very difficult to distinguish from its near ally P. ang^darc, and yet viewing the 



British terms, they appear to bo distinct. Indeed, were it otherwise, a series varying through every 



gn.dat.on from pinnate to tripiunata must bo united, and all hope of defining a species would be alan end 



While thus admitting the difficulty of discriminating between 80mc form* of these species, and without 



presuming to lay down any infallible rule for effecting this object* wo may point out how tboy may with 



tolerable certainty be known from each other, presuming that in the application and appreciation of 



the distinguishing peculiarities some gcncml knowledge of the plants is desirable : 1. P. aedcatum is 



a stouter, more erect, and altogether more rigid plant than P. angulare, which is normally lax and 



herbaceous, equally large or even larger in its size, 2. P. aenfmtum has its pinnules cither continent 



or deenrrent, in which cases there is no difficulty whatever in distinguishing it ; or when the pinnules 



are distinct, as in the most perfect plants, they are wedge-shaped at the base, the anterior side being 



truncate, and the posterior obliquely incised in straight lines, the two lines describing an acute angle by 



the apex of which they arc attached to the rachis. In />. angular* the truncated anterior base has a 



more curved outline, and the two lines of the base describe a right angle or an obtuse angle, at the apex 



of which is a distinct slender petiole, by which thoy are attached. 3. P. aculeatum has its sori medial, 



that is, attached at a point along the middle part of tho venule ; it is in fact nearer the base of the 



venule, i. c, the point of furcation, than the apex, which is carried out to tho margin of tho pinnule. In 



P. ungulate tho fertile venule stops about midway across the pinnule, and tho sorus is commonly placed 



at or almost close to its apex. These peculiarities observed in connection with each other will serve 



to reduce the dubious forms within very narrow limits indeed, at least* so far as British examples 



are concerned. The portion rather below the middle of the frond should be taken for examination. 



This is one of the most easily cultivated of all the larger hai-dy ferns. It prefers a loamy soil and 

 partial shade ; and is increased readily by division. Being evergreen, its varieties arc among the most 

 desirable of our native species for tho decoration of shady walks and rockeries, in which latter situation 

 especially, where the roots are generally well drained, provided tho plants aro not exposed to the 

 effects of severe drought and are moderately shaded, they thrive admirably. It is also very manageable 

 as a pot plant* and under any circumstances is ornamental in its character. The smaller form, known 

 as lob<Uum, is perhftps the most suitable for pot culture, on account of its size and tho elegance of its 

 fronds, which not uncommonly assume a very graceful lateral curve. 



Tho allied /». lonchilis, though a vigorous looking and hardy plant in its native haunts, is seldom 

 seen to preserve its vigour under cultivation, at least in tho neighbourhood of London, probably on 

 account of the impossibility of imitating the pure atmosphere of its native mountains. It certainly 

 prefers a damp atmosphere ; and, provided the moisture is not stagnant* its roots too should bo 

 freely supplied ; they should in fact be constantly moist with percolating moisture : and hence the 

 necessity of a careful mechanical adjustment of the materials employed as compost, of which mellow 

 loam, gritty sand, and small massos of some porous body, such as soa sandstone, should be tho main 

 ingredients. We have succeeded tolerably well by potting the plants very firmly in such a compost with 

 a small proportion of peat added, the plants being kept under glass in a close cold shaded frame, but 

 the removal of tho plants for the winter to a cold greenhouse where tho atmosphere was drier, led to 

 the partial decay of tho fronds. Tho same plants however on being enclosed within a handglass, 

 where consequently the atmospheric moisture was more abundant and regular, grew vigorously : so 

 that wo have no doubt tho requirements of this *]>ccies are a well moistened but freely-drained soil and 

 a damp atmosphere, which can only be secured in many cases by keeping the plants close under glass. 

 Propagation is rarely to be effected by division, lateral crowns being seldom produced ; consequently, 

 plants generally have to be obtained from their native habitats. As it fructifies freely, they might bo 

 raised from the s|>oros. 



There are various degrees of development in this secies, some of tho most distinct of which have 



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