Teleutos-pores. 23 



CHAPTER VII. 



TELEUTOSPORES. 



Teleutospores are very varied in their shape and size, and are on that 

 account often regarded as the characteristic form for distinguishing genera. 

 They may be produced directly from ithe mycelium of the aecidiospore or 

 uredospore, or indirectly from the teleutospore itself by means of the 

 sporidiola. As the name denotes, it is the last formed, or finishing spore, 

 in the life-history of rusts, although in many instances it is the only spore 

 formed, and there are cases where it has not yet been found. Where 

 it exists alone it may be that the other spore-forms originally existed, but 

 have now come to be dispensed with, and where it does not exist it may 

 be a degenerate type like the other, only it is the teleutospore form which 

 has been dropped. It is a question, however, whether it is not a necessary 

 stage in the life of every rust, and its apparent absence is simply owing to 

 our not having discovered it. 



As an example, Uredo symphyti, D'C. was considered by De Bary to 

 be an independent species, and having lost its other spore-forms to be 

 capable of existing without them, but Bubak 2 afterwards found the teleuto- 

 spore in Bohemia, and so it may turn out in other cases. 



They arise like the uredospores in smaller or larger spore-beds, often 

 closely crowded together, and usually directly beneath the epidermis which 

 they often rupture. It is seldom that they originate directly beneath 

 the cuticle. The colour of the spore layer is very variable, hut generally 

 it is darker than the uredo layer, being dark-brown to blackish, and only 

 rarely reddish. 



In the simplest cases teleutospores are unicellular, and originate in a 

 similar manner to the uredospores. The spore-bed, consisting of inter- 

 lacing and crowded hyphae, gives off erect branches, which become 

 swollen at their free ends, and the finely granular protoplasmic contents 

 are invested by an inner membrane, or endospore, in addition to the outer 

 or epispore, which becomes relatively thick and dark in colour. The 

 teleutospores are generally formed towards the end of the active vegetative 

 period of the host-plant, and are often called winter spores in contrast 

 to the uredo or summer spores. They are specially adapted and equipped 

 for continuing the species over periods of drought, or damp, or cold, or 

 seasons of scarcity. This is seen in the firm outer wall, which is often 

 sculptured in various ways, as well as in the reserve material stored up in 

 the contents. Sydow 1 states that in all Leptopuccinieae, or those only 

 possessing iteleutospores which germinate at once, the epispore is perfectly 

 smooth; but there is one exception in Australia P. plagianthi. In other 

 groups the epispore may be smooth, warted, striated, &c. 



The portion of the hypha supporting the spore becomes the stalk, or 

 pedicel, by means of which it (remains attached to the spore-bed for a 

 longer or shorter period. 



In Endophyllum the teleutospores originate in chains, and are produced 

 within a peridium similar to aecidia. They would be called aecidiospores, 

 only they produce a fouir-celled promycelium, which bears promycelial 

 spores. They serve the purpose of summer spores, since they germinate as 

 soon as they are ripe, and the fungus winters by means of its mycelium 

 in the host-plant. 



438. 



