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Chytridiaceous Fungi with Unusual Sporangial

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Chytridiaceous Fungi with Unusual Sporangial July, 1938] SPARRO\V-CHYTRIDIACEOUS FUNGI 485 ovary, while in the Gentianaceae proper there is found tianaceae often show fusion of vascular traces in the no such close approach to true epigyny. receptacle to form concentric bundles of a distinctive Jillenyanthes and Nephrophlltlidium are closely re­ type. Vascular fusion in the Menyanthaceae takes a lated genera, while Nimvphoidee and Villarsia stand different form, producing a definite horizontal ring together on another short branch of descent. The by cohesion and adnation, this structure being unique last named of each pair is the more highly specialized, in floral anatomy. Additional floral characters of the as indicated by the extent of fusion, both external Menyanthaceae which distinguish this group from the and vascular. These four genera, together with the Gentianaceae are: (1) presence of ovule traces, (2) allied Lipa1'Ophll11um, form a very coherent group. fusion of adjacent corolla" laterals, (3) bilaterally Although they show a stronger affinity with the symmetrical vascular pattern, and (4) epigynous in­ Gentianaceae than with any other family, their ana­ sertion of floral parts in certain genera, accompanied tomical peculiarities and the absence of various by extreme vascular fusion. Several significant non­ specializations found generally throughout the Gen­ floral traits characterizing the Gentianaceae (siphono­ tianaceae strongly supports the separation of this stele, amphicribral bundles, anomalously placed sieve group as a distinct family, the Menyanthaceae, estab­ tubes, and storage of calcium oxalate crystals) are lished by Don in 1838. lacking in the Menyanthaceae. It is concluded that SUMMARY the latter group merits full family status. The validity of the Menyanthaceae, as distinct DEPARTMENT m' BIOLOGY, from the Gentianaceae, is considered from the stand­ AMERICAN UNIVERSITY, point of anatomy. The advanced genera of the Gen- WASHINGTON, D.C. LITERATURE CITED BRITTON, N. L., AND A. BROWN. 1897. An illustrated PERROT, EMILE. 1897. Anatomie comparee des genti­ flora of the northern United States and Canada. anees aquatiques. Bull. Soc. Bot. France 44. 'N~w York. --. 1898. Anatomie comparee des Gentianacees. DON, G. 1838. General history of dichlamydeous plants. Ann. Sci. Nat. Ser. 8. 7: 105-292. Vol. 4. London. WETTSTEIN, R. 1935. Handbuch der systematischen GILG, E. 1895. Gentianaceae, in Engler and Prantl: Botanik. Vol. 2. Die naturlichen Pflanzenfamilien. Pt. 4, div. 2: 50­ WILSON, C. L. 1937. The phylogeny of the stamen. 108. Leipzig. Amer. Jour. Bot. 24: 681Hi99. GRELOT, M. P. 1898. Recherches sur Ie systeme libero­ WOODSON, 'R. E. 1936. Observations on the floral fibres ligneux floral des gamopetales bicarpelles. Ann. Sci. of certain Gentianaceae. Annals Bot. 50: 759-766. Nat. Ser. 8. 5: 1-154. CHYTRIDIACEOUS FUNGI WITH UNUSUAL SPORANGIAL ORNAMENTATION 1 F. K. Sparrow, Jr. AMONG THE aquatic orders of the Phycomycetes, The latter, found on the sporangia of the so-called there are included in the Chytridiales some of the " dentigerate" species, is perhaps the most curious most curious of the fungi. Not only are these un­ of all and is remarkable for its delicate beauty and usual in their choice of substrata, as, for example, precision of arrangement. the empty integuments of the larval stages of aquatic Relatively early in the investigations on chytri­ insects, pollen grains, other aquatic fungi, algae, eel diaceous fungi, Rosen (1887) described the first of the worms, rotifers, etc., but also in their possession of algal-inhabiting, dentigerate species. These all pos­ remarkable and often bizarre structural' features. sessed on the extramatrical, usually sessile sporan­ For example, on their reproductive parts (sporangia gium, a crown of four small bipartite teeth which and resting spores) some species develop unusual surrounded the apical exit pore. A further character­ types of ornamentation which may take the form of istic of Rosen's fungi was the presence within the spines, knobs, long, branched or unbranched hairs, algal cell directly beneath the sporangium of a swell­ broad rays, one or many spines arranged radially or ing or apophysis which, from the figures given, arose in a helical series, irregular solid lobes, anastomosing as a result of the expansion of a portion of the ridges, or apical collarettes of plain or bipartite teeth. already established rhizoidal system. To this small 1 Received for publication April 23, 1938. group of three species, Rosen applied the name Paper from the Department of Botany, University of " Dentigera" and considered it a distinct section of Michigan, No. 659. Chlltridium in the older, inclusive sense of that genus. Acknowledgment is made to the Faculty Research Fund of the University of Michigan for aid given in The species, all of which were found on Green Algae, preparation of this paper. may be characterized as follows: AMERICAN JOURNAL OF BOTANY tvei 25, Chytridiurri Zygneinatis. Rosen, sporangium spheri­ and obviously dead algal filaments, and all were able cal or ovate, the four teeth short, delicate, and to maintain themselves in varying degrees on boiled strongly convergent. On Zygnema. plants of Cladophora and Oedogonium. dentatum Ch.utridium. Rosen, sporangium more PHLYCTOCHYTRIUM PLANICORNE Atkinson. - This elliptical, the four teeth more prominent and soon fungus, described in 1909 by Atkinson on Spirogyra converging On Spirogyra. Chytndium quadricorne de Bary (from de Bary) , varians, has as its distinctive feature an apical crown sporangium short, cylindrical on a rounded base, of four plain teeth surrounding the exit pore of the with truncate apex, the 'four teeth prominent, long sporangium. The extramatrical body was described and scarcely convergent. On Oedogonium. as broadly elliptical, 6 X 8 tJ., and the intramatrical part as consisting of a globose apophysis 3 tJ. in diam­ 0fthese species, only C. Zygnematis seems to have eter, from which several branched, feebly developed been studied in any detail. Numerous figures, show­ rhizoids radiated. The zoospores were not seen. In ing " mehrblasige Formen" (non-sessile, probably ab­ 1932 (Sparrow) I described material of this species normal plants), "Frostsporangien" (detached young found on Rhizocionium heiroglyphicum at both Cold sporangia of non-sessile plants which, although frozen Spring Harbor, Long Island, New York, and Cam­ in the ice, remained viable), and the formation of the bridge, Massachusetts, which had narrowly to broadly zoospores, are given. ovate sporangia, differing little from Atkinson's fungus All these species, as well as other, similar ones with in size but usually being longer than wide. The teeth apophysate inoperculate sporangia and posteriorly were plain and four in number, and the intramatrical uniciliate zoospores, were later placed by Fischer apophysis varied from a slender fusiform enlargement (1892) in the genus Rhizidium, but were removed to a definitely spherical structure. The rhizoidal sys­ from this group by Schr6ter (1897) (who correctly tem as well showed considerable differences in degree interpreted Rhizidium) and placed in a new genus, of development, consisting in some cases of a few Phlyctochytrium. tenuous, branched threads emerging from the surface In the more than fifty years since their discovery, of the apophysis, while in others it was extensive and these dentigerate chytrids have evidently been seen relatively stout, particularly where it joined the sub­ but rarely (de Wildeman, 1896; Sparrow, 1932, 1933, sporangial swelling. The zoospores emerged partially 1936; Karling, 1932; Dorman, 1936), and only a few differentiated, apparently surrounded by a vesicle, new species 2.have been described (Rhizophidium Bre­ and after completing their development outside the b~8S0n!~ (Dang.) Fisher, R. digitatum Scherff., R. Hya­ sporangium, burst 'the vesicle and swam away. loihecae Scherff., etc.). In most cases, because of The present material was found in greatest abun­ fragmentary observations, .these new fungi are diffi­ dance on dead, colorless filaments of Cladophora and cult to place generically. However, Phlyctochytrium to a lesser degree on Oedogonium, in company with planicorne, described by Atkinson (1909), is an un­ Catenaria sp., Rhizophidium chaetiferum Sparrow, questioned member of the Dentigera, distinct from Diplophlyctis laevis Sparrow, and the other denti­ the others in the possession- of a crown of four plain, gerate species shortly to be described. not bipartite teeth. The recently described P. des­ The establishment of the thallus and its subsequent midiacearum Dang., from the' scanty information development were not observed in great detail but given of the sporangial state, seems doubtfully dis­ were essentially as follows: The body of the quiescent tinct from P. quadricorne ; it is of interest, however, zoospore on the outer surface of the alga produces a from the fact that it is unquestionably capable of slender tube which penetrates the wall for a varying attacking living desmids which respond to the incur­ distance before branching (fig. 1). Coincident with sionsof the fungus (as Scherffel, 1925, has observed this, the extramatrical part becomes somewhat nar­ in other instances) by the formation of wall material rowly ellipsoidal, and on it there are soon visible four around the penetration tube of the invader. Smooth­ apical protuberances (fig. 1). Further development walled, spherical, extramatrical resting spores were of the rhizoidal system involves the elongation, branch­
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