480 CLASS BASIDIOMYCETEAE 



the genus Pterula. Eriocladus (Lachnodadium) is larger, with flattened 

 or rounded branches which are hairy. Some of the much branched fleshy 

 species of Clavaria have been set off as separate genera: Clavulina and 

 Clavariella (Ramaria). The majority (but not ah) of the species of these 

 two genera are respectively stichobasidial and chiastobasidial. Gaumann 

 (1926) and Donk (1933) accordingly place Clavulina in a distinct order, 

 the Cantharellales, along with some segregates from the Thelephoraceae 

 and Hydnaceae and Agaricaceae. The genus Clavicorona, with apices of 

 the branches truncate or cup-shaped, and with gloeocystidia in the 

 hymenium layer has been set apart from Clavaria by Doty (1947). 

 (Figs. 156, 157.) 



Family Exobasidiaceae. The fungi composing this family are para- 

 sitic in the leaves, green stems or even fruits of higher plants, often 

 distorting the affected parts or causing the formation of galls. The inter- 

 cellular mycelium apparently bears no clamp connections. It sends rod- 

 shaped or branched haustoria into the host cells. The basidia arise singly 

 or in tufts between the epidermal cells, eventually piercing the cuticle 

 and forming their usually four to eight spores externally. There are no 

 paraphyses or cystidia. Eftimiu and Kharbush (1927) have made an 

 extensive study of a species of Exobasidium. The mycelial cells within the 

 host are elongated but become shorter nearer the epidermis and there are 

 binucleate. The fusion nucleus in the basidium divides meiotically into 

 four nuclei, one passing into each basidiospore. The nuclei may divide 

 before the spores are formed and then the eight nuclei enter eight basidio- 

 spores. Sometimes one nucleus of the four degenerates and the remaining 

 three divide so that six spores are formed. Sometimes only two nuclei are 

 found in the basidium and then only two basidiospores. These spores 

 germinate by budding like yeasts often becoming once septate first. In 

 E. rhododendri Cramer, the spores divide by a septum and send out germ 

 tubes from each of the two cells thus formed. In this species the nuclear 

 divisions within the basidium may be either stichobasidial or chiasto- 

 basidial. Gadd and Loos (1948) report that in E. vexans the basidiospores 

 become once septate before they are discharged. These two-celled spores 

 may develop thick walls after becoming free. E. vaccinii (Fuckel) Wor. is 

 frequent upon the cranberry (Oxycoccos macrocarpus (Ait.) Pursh) and 

 related plants. The affected shoots become upright and take on a pink 

 color and the leaves are increased in size and the stem thickened. Some- 

 times only a small portion of a leaf may be infected or a spot on one side 

 of a fruit. Such spots are thickened and reddened. The basidia are club- 

 shaped with four basidiospores which become septate before germination 

 and send out short branching sterigmata bearing spindle-shaped spores. 

 About 30 species are known in this genus. The genus Kordyana probably 

 also belongs in this family. It is tropical. The basidia are two-spored, 



