A MONOGKAPH OF THE GENUS POD AXIS Desv. 

 (= POD AXON Fb.). 



By George Massee. 



(Plates 294 & 295.) 



The genus Podaxis has up to the present been considered as 

 typical of the Gastromycetes, which, with the Hymenomycetes, 

 constitute one of the primary divisions of Fungi known as the 

 Basidiomycetes, characterised by having the spores produced from 

 the apices of large clavate cells or basidia. The receipt of a batch 

 of Podaxis indica Spreng. (= Podaxon pistillaris Fr.), from South 

 Africa, including some very young specimens, has led to the 

 unexpected discovery that the spores are produced in asci, conse- 

 quently the genus belongs to the Ascomycetes. The species of 

 Podaxis are amongst the largest of fungi, and so close is the 

 general appearance to that presented by typical Gastromycetes, that 

 they have hitherto been mistaken for long-stalked puff-balls, with 

 stems varying from ten to fourteen inches high, and half-an-inch or 

 more in thickness ; the head is usually ovate, from three to seven 

 inches high, and at maturity filled with a dense powdery mass of 

 spores, usually mixed with threads. In Saccardo's ' Sylloge Fung- 

 orum ' the genus Podaxon is given as the type of a tribe of Gastro- 

 mycetous fungi called Podaxinea, It may be stated that all the 

 genera included in the above-named tribe, with the exception of 

 Podaxis, belong to the Gastromycetes. 



Morphology. 



Differentiation of the gleba up to the escape of the spores from 

 the asci takes place while the fungus remains under ground. The 

 youngest specimen examined was broadly elliptical, 2 cm. high by 

 1*5 cm. in diameter, and furnished at the base with a white, 

 cobweb-like mycelium that had bound together the sand into a 

 compact bulb-like mass. At this stage the plant consists of a 

 homogeneous weft ; the component hyphae are richly supplied with 

 densely granular, vacuolated protoplasm ; the walls are very thin, 

 and transverse septa numerous. The average diameter of the 

 hyphae is about 6 fi, but in numerous instances certain cells become 

 inflated into a more or less spherical or pyrif'orm shape, and many 

 of the blind ends of lateral branches terminate in a broadly obovate 

 cell (fig. 8). The walls of the hyphae become violet at once on the 

 application of sulphuric acid and iodine. The hyphae run mostly in 

 the direction of the axis of growth, giving off numerous lateral 

 branches, which thread irregularly between the ascending primary 

 hyphae, and usually terminate in blind ends. The weft is compact, 

 but the hyphae are not crowded, and there are many small, irregular 

 interstices containing air. When the fungus has reached a height 

 of 5 cm. with a diameter of 3 cm., a vertical median section shows 

 a considerable amount of internal differentiation, and strongly 

 recalls to mind the appearance of a section of a young agaric 



Journal of Botany. — Vol. 28. [Feb. 1890.] d 



