XL] DIACALPE 105 



types may be found, the largest providing the three-rowed, and the smallest 

 the one-rowed stalk (Fig. 649, A,B,C). The annulus of the mature sporangium 

 is indurated on one side, down to the insertion of the stalk where it is in- 

 terrupted. On the other side is the stomium composed of four cells. Attached 

 to the stalk of many of the sporangia is a hair, often glandular : these hairs 

 are very like those of Dryopteris filix-inas, a fact of some comparative 

 importance. 



DiACALPE Blume 



The single species D. aspidioides Bl.. from tropical Asia, is still maintained 

 under the name by .which it was first defined by Blume in 1828. It has, it 

 is true, borne several other synonyms from time to time, and even been 

 included in Cyathea (Moritz, 1845). This stamps a relationship that is 

 probably a real one, though the unanimity of later writers is a witness to 

 the distinctness of type. On the other hand, various species of Woodsia have 

 from time to time been included under Diacalpe, a fact which points to a 

 near relationship with that genus. Thus the systematic treatment oi Diacalpe 

 suggests that it is an interesting intermediate though distinct survival. 

 Its vicissitudes of systematic place and designation are fully abstracted by 

 Davie, and need not be repeated here {Ann. of Bot. XXVI, 1912, pp. 255-6). 



The adult stock is upright, on which are inserted leaves 2-4 feet long, 

 densely scaly below, with a tripinnate blade bearing long hair-like scales 

 and hairs when young. The venation is open, and the veinlets undivided 

 (Fig. 650, A, B). The sori are usually seated on the lower anterior veinlet 

 of each segment, below its termination: they are sessile, and protected by 

 an enclosing indusium. Each contains about 100 sporangia, the ages of 

 which are intermixed. 



The stock is traversed by an advanced type of dictyostele, but without 

 perforations (Davie, I.e. p. 258). The leaf-trace consists of three main strands 

 with a varying number of subsidiary bundles, and it is inserted on the 

 lower half of the leaf-gap. Thus in essentials the vascular system corresponds 

 to those o{ Peranenia and Dryopteris filix-mas. 



The adult sorus is entirely covered in by the basally-attached, coriaceous 

 indusium, as in Cyathea (Fig. 650, B, C). The convex receptacle, which 

 contains a button-shaped vascular supply, bears sporangia of mixed ages; 

 but there is no evidence of their basipetal sequence. The sporangium itself 

 is borne upon a long three-rowed stalk : its head is encircled by a slightly 

 oblique annulus, interrupted at the insertion of the stalk, and with a lateral 

 well-organised stomium (Fig. 651). The slight obliquity of the annulus 

 makes it possible to distinguish between the proximal and distal faces, as 

 in Dryopteris and others (Vol. i, pp. 254-5). Hairs are sometimes present on 



