XXXIX] LLAVEA. CRYPTOGRAMME 65 



I. The Primitive Gymnogrammoid Ferns 



Llavea Lagasca 



Llavea is a monotypic genus. Its single representative is L. cofdifolia 

 Lagasca, a native of the Mexican uplands, figured by Sir W. Hooker {Gen. 

 Fil. Tab. XXXVl). The ascending stock and leaf-bases bear hairs and scales. 

 The leaves are spirally arranged and long-stalked, and they may be tri- 

 pinnate. The lower pinnae are sterile, vi^ith segments of the Osmundaceous 

 type, having forked venation. The upper are fertile with inrolled margins, 

 giving an appearance as in Plagiogyria. The very numerous sporangia are 

 inserted along the veins, as in Gyninograiinne^ and they are fully protected 

 by the leaf-margin till mature (Fig. 624), The stock is traversed by a slightly 

 dictyostelic solenostele, as in Plagiogyria: the vascular ring is sometimes 

 complete when seen in transverse section. The leaf-trace departs as a single 

 strap, which shortly after separation is seen to be tetrarch, and the pinna- 

 traces are marginal in origin (see Thompson, 647, Text-figs. 8-1 1). In these 

 structural points Llavea compares with Plagiogyria: but there is no basal 

 enlargement of the leaf-stalk, and pneumatophores are absent. 



The sporangia are pear-shaped, with a three-rowed stalk, but the annulus 

 and stomium are variable. Sometimes the annulus is vertical and regular, 

 but this is relatively uncommon. Frequently it passes obliquely, being inter- 

 rupted in its course, and its cells being even bi-seriate at some points. This 

 instability is a feature shared by other related Ferns, and especially by 

 Cryptograniine. The spore-counts give figures 46-52, indicating a typical 

 number of 48-64. For further details reference may be made to Dr J. McL. 

 Thompson's Memoir (647). 



CRYPTOGRAMME R. Brown 



Cryptograniine is a wide-spread genus, with 4 species, of which C. crispa 

 (L ) R. Br., the Parsley Fern, is native in Britain. It shares many of the 

 features of Llavea, but on a smaller scale, and the two genera have habitually 

 been classed together. Here, however, the sori occupy the vein-endings 

 (Fig. 624, U). The Parsley P^ern has a creeping rhizome bearing dermal 

 scales, and spirally arranged leaves that are 2-4 pinnate (Fig. 625, A). It 

 is dictyostelic, a state consequent on the close arrangement of the leaves, 

 and each leaf-trace is an undivided meristele. The venation is open, with 

 anadromic branching: thus in essentials the structure is as in Llavea, but 

 smaller. The similarity extends also to the fertile segments (Fig. 625), The 

 chief interest lies in the varying details of the sporangia, which are pear- 

 shaped. They arise superficially, close to the vein-endings, and without any 

 vestige of an indusium: moreover there are indications of a "mixed" condi- 



BHI 5 



