430 DR LAUDER LINDSAY ON THE 



Genus III. jEcidium. 

 Sp. 1. M. Otagense (figs. 61 to 74). 



1. Parasitic on the flowers, flower-petioles and leaves of Clematis hexasepala, 

 DC. East Taeri Bush ; Novem. ; in abundant flower; a beautiful bush-climber, 

 known to the Maoris as the " Puawananga," or " Poananga." 



The flowers and flower-petioles are completely deformed by the growth of the 

 parasite; their aspect is so entirely changed, that were the diagnosis of the 

 plant dependent on specimens possessing these diseased organs, its species and 

 genus would probably not be recognisable. The filiform or slender petioles, in 

 particular, not only become twisted and curled variously, but are the seat of 

 irregular, succulent, gouty swellings — of cucumber or cactus-like growths (figs. 

 61 a, 62 c), whose nature is rendered apparent by the beautiful buff-coloured 

 Peridia, by which they are covered. 



When the flower is the seat of the parasite, the sepals become thickened and 

 somewhat coriaceous or fleshy, at least toward their bases or insertions. They 

 also acquire adhesions to each other at their proximal ends, forming a sub-cam- 

 panulate or sub-urceolate perianth (fig. 62 a). On the outer surface of the sepals 

 the Peridia exhibit themselves as Urceolce (fig. 66 a), resembling the cyphellse of 

 some Stictw ; while, on their internal surface, the position of each urceole is 

 marked by a corresponding papilla (fig. 66 b). When the Fungus occurs on the 

 leaf of the Clematis (fig. 63), it alters its texture and appearance to this extent, 

 that the leaf becomes thickened and coriaceous ; its margin notched, thickened, 

 and curled up (a) ; and its colour assumes a russet-brown or faded autumnal tint. 



In the young state, the Peridia appear as epidermal papillae (figs. 6b, 67 a), 

 gradually pierced by an apicial ostiole, which rapidly expands into an urceola 

 (figs. 66 a, 65 and 67 b), developing or exposing the concealed disk. Frequently, 

 also, they are verruciform or disk-like, having a more or less flat surface, with 

 or without a thick, rounded, prominent rim (figs. 64, 65, 67 c). Normally, in the 

 mature and old state, the Peridia are urceolate ; their disk being sunk below the 

 level of the epidermis of the Clematis ; with raised margins projecting above the 

 same level, varying much in thickness (fig. 67 b). Sometimes this margin is as 

 thick as the apothecial exciple of many Lecanora? ; at other times it is thin and 

 sub-membranous. Normally, the shape of the Peridia is round ; but from pressure 

 on each other, when more or less closely aggregated, they become variously ellip- 

 soid or elongated (fig. 64 d). They vary greatly in their numbers and closeness 

 of aggregation. Sometimes they are isolated, or occur in twos or threes (fig. 63), 

 or in very small, scattered groups. This is the case on the leaf of Clematis in 

 my specimens. At other times they are so closely crowded, that there is left 

 between each Peridium no intervening tissue of the matrix (figs. 61, 62, 64). 



