194 Transactions. 



Section Phlegmaria. 



L. Billardieri Spring ; L. Billanlien var. gracile T. Kirk ; L. varium R. Br. 



Prodr. 



Literature. 



The first papers published on the prothalli of this section were those 

 of Treub (14, 15) dealing with the four tropical species L. Phlegmaria 

 Linn., L. carinatum Desv., L. H ippuris .Desv., and* L. nummularifolium 

 Blume. In a paper on the stem-anatomy of certain New Zealand species 

 of Lycopodium I gave a very brief description of the prothallus of L. Bil- 

 lardieri, stating that it corresponded to the Phlegmaria type (6), and Miss 

 Edgerley a few years later (4) described it more fully, with figures. In two 

 papers of the present series (7, 9) I have given certain details concerning 

 the external form and the structure of this same prothallus and of the two 

 allied forms L. Billardieri var. gracile and L. varium. Literature dealing 

 with two species of prothallus belonging to the closely related Selago section 

 must also be mentioned — viz., Bruchmann's two accounts (1, 2) of the 

 prothallus of L. Selago Linn., and a very brief description, with one figure, 

 of that of L. lucididum Michx. by Spessard (11). 



General Form of the Prothallus. 



The complete mature prothallus of all these three New Zealand forms, 

 similarly to those of the four tropical epiphytic species described by Treub, 

 consists essentially of a central body of tissue, which may be either bulky 

 or more or less elongated, and a number of branches which arise adventi- 

 tiously from this central body. In fig. 1 is shown such a complete hiature 

 prothallus of L. Billardieri var. gracile in external view, the natural size' 

 being also indicated in the illustration. The central body of the prothallus 

 as here shown is somewhat slender and elongated, a condition which I have 

 found generally to be the rule in this variety. It possesses two complete, 

 and also two broken, thin vegetative branches ; a young, stouter branch ; 

 and also, nearer the forward end, a short club-shaped " resting " process. 

 The two complete branches on the left side of the figure have begun to put 

 forth secondary branches, while otie has also commenced to expand at its 

 growing end preparatory to there bearing sexual organs. The oldest end 

 of the prothallus is intact, and shows clearly the original cone form with 

 which the prothallus of the epiphytic type always begins. At the apex of 

 the cone the cell first formed from the spore still persists. The main pro- 

 thallial body shows the presence of fungus in its internal tissues, this fungal 

 inhabitant occupying the whole of the tissues in the dark basal cone-like 

 region, but being more irregularly distributed farther forward. The fungus 

 is also present in the vegetative branches, being there also somewhat irre- 

 gularly distributed, and the single club-shaped resting process is very dark 

 with it. The ends of the branches are all quite free of fungus and are 

 translucent in appearance. The forward end of the main prothallial body is 

 sHghtly more bulky than the rest, and is quite clear of the fungus. This is 

 the main generative region of the prothallus, and bears paraphyses, archegonia, 

 and also a young plant. The whole prothallus is covered with long rhizoids 

 inclining forward towards the growing apices, except on the terminal bulky 

 region, which is wholly devoid of jbhem, and on the basal cone-Hke region, 

 from which they have decayed away, leaving only short, stubby pro- 

 jections. The description of this particular prothallus in its external 



