42 



PLASMODIOPHORALES 



is lacking in Rostrup's, Winge's, and Palm and 

 Burk's figures of cystosori. Cook's ("33, PI. 6, fig. 9) 

 own photographs of S. J'eronicae fail to show a dis- 

 tinct membrane. Nonetheless, he has often contended 

 that it is present and has used ('33) the presence of 

 this structure as one of the distinguishing generic 

 characters of Sorosphaera as well as Sorodisciis. In 

 the original diagnosis of the genus. Schroeter de- 

 scribed the cystosori as being surrounded by a com- 

 mon cuticle, and this may be partly responsible for 

 Nemec's ('H) and Cook's contention as to the pres- 

 ence of a membrane. Webb described it as being 

 formed after the spores had developed their individ- 

 ual walls, but he gave no figures of its development. 

 Winge ('13, p. 30) denied its existence, while Blom- 

 field and Schwartz as well as Maire and Tison, who 

 have so far made the most extensive study of the 

 genus, said nothing about it. It is quite probable 

 that the adjacent lateral walls of the spores become 

 more or less fused by mutual pressure as they de- 

 velop, and this prevents the spores from separating 

 readily at maturity. The best cytological data in the 

 literature to date do not, therefore, support Cook's 

 view on the presence of a membrane, and the use of 

 this structure as a diagnostic generic character is at 

 present open to serious question. 



The cvstosori of S. J'eronicae are predominantly 

 hollow spheres and ellipsoids, but numerous varia- 

 tions in shape have been noted by Maire and Tison, 

 Trotter, Webb, and others. Palm and Burk in par- 

 ticular found them to be unusually variable in galls 

 on r. americana collected in Colorado, U. S. A. In 

 this material they found the cystosori to be three 

 principal shapes: hollow spheres, flattened ellip- 

 soids, and irregular sponge-like masses, and between 

 these types all degrees of variations and intergrada- 

 tions were observed. As is shown in figures .52 to 57, 

 the Sorosphaera- or hollow-sphere type predomi- 

 nated, but two-layered flattened discs as in Soro- 

 disciis (fig. 53, 54), spongy masses with narrow or 

 wide channels as in Spongospora (fig. 55, 56), and 

 irregular masses of indeterminate shape as in Lig- 

 niera (fig. 57) were not uncommon. Likewise within 

 the same sorus, spores with smooth and verrucose 

 walls were present (fig. 53, 55, 57). Palm and Burk 

 accordingly concluded that the shape of the cysto- 

 sorus and the relative arrangement of the spores are 

 governed largely by environmental conditions and 

 that the size and shape of the host cell are determin- 

 ing factors. They furthermore concluded that since 

 sori typical of those of Spotu/ospora, Sorodisciis, 

 Ligniera, Osienfeldiella, Claihrosoriis, and Mem- 

 hranosoriis may all be found in S. J'eronicae, these 

 genera should be regarded as synonyms of Soro- 

 sphaera. Fitzpatriek ('30) believed that Ligniera 

 also should be incorporated in Sorospftaera on the 

 grounds that the only difference between the two is 

 that the former causes no hypertrophy of the host. 



In 1907 Speschnew (p. 22, PI. 2, fig. 7-12) de- 

 scribed a species on tea leaves in the Caucasus which 

 he named Sorospliaera tlieae. Two years later, how- 

 ever, Ducommet ('09) reported that no organism is 



present in the leaves and that the so-called spores 

 are only tannin deposits in the cells. Fitzpatriek re- 

 ferred to this species as PlasmodiopJiora Theae. 



S. VERONICAE Schroeter, I.e. 



Tiihirciiiia f'erouicae Schroeter. 1877. Beitr. Biol. Pflanz. 



;? : 383. 

 Sorusporiiim Veronicae Winter. 188-t. Die Pilze Deutsch- 

 lands, Oesterreich und der Schweiz 1 : 103. 



Cystosori bright brown, one to several in a cell, 

 variable in size and siiape, predominantly in the 

 form of hollow spheres, ]8-42(a, occasionally elon- 

 gate, flat and disc-shaped, irregular and indeter- 

 minate, compact or loose and spongy with numerous 

 ramifying channels, composed of from four to 61 

 spores. Resting spores ovoid, pyramidal, urn-shaped 

 1-5 IX X 8-9 fx., with brown, smooth or verrucose 

 outer walls, often surmounted by an apical collar. 

 Zoospores biflagellate and heteroeont. Plasmodia one 

 to several in a cell, 20-30 /i, schizogony doubtful; 

 producing a single cystosorus. Zoosporangia un- 

 known. 



Parasitic in J'eronica hederaefolia, J', cliamae- 

 drifs, and /'. triphifUos in Germany (Schroeter, '77, 

 '86, '97 ; Winter, I.e. ; Diedieke, '11; Grevillius, '13) ; 

 /'. saj-atilis, J', officinalis, J', hederaefolia, J', scii- 

 tellata, J'. Beccahiinga, J'. Anagallis, J', aqiiatica, 

 J'. serpi/Uifolia, and /'. Chaemaedri/s in Finland, 

 Norway and Sweden (Lagerheim: see Winge, '13; 

 Palm, '08) ; J\ hederaefolio in Sehleswig-Holstein 

 and Denmark (Hennings, '91 ; Rostrup, '94) ; T. 

 Chamaedri^s in France (Maire and Tison, '08, '09, 

 '10, '11; Maire, '10); /'. Chamaedrys in England 

 (Blomfield and Schwartz, '10; Cook and Schwartz, 

 '29) ; r. arvensis and J', hederaefolia in Italy (Trot- 

 ter, '04, '16); r. americana and J', arvensis in the 

 U. S. A. (Palm and Burk, '33; Donald, '34), caus- 

 ing tumors up to 5 mm. in diameter on the stems, 

 petioles, and midrib of leaves. 



This species was first described by Schroeter in 

 1877 as a member of the Ustilaginales under the 

 name Tuhercinia J'eronicae, and in 1884 ^^'inter 

 transferred it to the genus Sorosporium. In 1886, 

 however, Schroeter created the genus Sorosphaera 

 for it and transferred it to his newly established 

 Phytomyxinae. Rostrup found it in Denmark in 

 1894 and replaced it in the Ustilaginales, and ac- 

 cording to Winge, Lagerheim found it in Norway 

 and Sweden on a large number of J'eronica species, 

 and as early as 1901, "and knew the correct system- 

 atic position of Sorosphaera." Trotter discovered it 

 in Italy in 1904, and while he questioned its inclusion 

 among the smuts, he also doubted that it is a mem- 

 ber of the Mycetozoa. The subsequent studies of 

 Maire and Tison and Blomfield and Schwartz clearly 

 showed that it belongs in the Plasmodiophoraeeae in 

 close relation to P. Brassicae. 



The tumors caused by S. J'eronicae vary from pin- 

 head size to 5 cm. in diameter and are usually com- 

 ])osed of a mass of healthy and infected undifferen- 

 tiated cells among which are intersjiersed a few spi- 

 ral and annular vessels. The galls are the result of 



