THALLOPHYTA: FUNGI 



135 



numbers of conidiophores, the conidia being carried by the wind to new 

 hosts. Later in the season small, red, flask-shaped ascocarps, called 

 perithecia, are developed on the stromata (Fig. 110). 



Claviceps. The common ergot disease of rye and other grasses is caused 

 by Claviceps purpurea. Its damage to the rye is usually slight, but the 

 eating of diseased grain by animals results in a paralysis and other serious 

 conditions. A drug derived from the fruiting bodies of this fungus, called 

 ergotine, has important uses in medicine. The ovaries of the rye are 

 infected by ascospores in the early summer and become hypertrophied, a 





Fig. 110. Stroma of Nectria cinnabarina on bark of Rihes, showing two perithecia with 

 young asci and paraphyses, X75. 



mycelium developing within. The formation of conidia soon follows. 

 The conidia are minute cells abstricted from the tips of short conidio- 

 phores. As they are formed, a sweet liquid is exuded from the spikelet. 

 This attracts insects, which carry the conidia to uninfected flowers. 

 Later the mycelium hardens to form a compact sclerotium, which replaces 

 the ovary of the flower. The sclerotia are elongated, slightly curved, 

 purplish bodies that project from the ears of the rye. Many of them 

 eventually fall to the ground, where they pass the winter. In the spring 

 the sclerotium produces several or many globular, stalked stromata, which 

 are compact mycelial masses containing numerous flask-shaped, deeply 

 embedded perithecia (Fig. 111). The entire stroma is cream-colored at 

 first, becoming grayish violet. Each perithecium is fined with a hyme- 

 nium consisting of many asci and paraphyses. The ascospores, which are 

 needle-shaped, are discharged forcibly and dispersed by the wind. 



The sex organs of Claviceps are borne on hyphae lying below the surface 

 of the stroma. The ascogonium is broader than the antheridium and 

 both are multinucleate. The contents of the antheridium enters the 



