38. PUCCINIA ESPINOSARA Diet. and Holw.

On Eupatorium espinosarum A. Gr., Oaxaca, Nov. 10, 1903, no. 5366: E. Smithii Rob., Oaxaca, Nov. 10, 1903, no. 5365.

39. PUCCINIA CONOCLINII Seym.

On Eupatorium Neaeanum DC., Etla, State of Oaxaca, Nov. 13, 1903, no. 5410.

40. Puccinia rosea (D. and H.), n. n.

On Eupatorium deltoideum Jacq., Amecameca, Oct. 20, 1903, no. 5202; Oaxaca, Oct. 21, 1899, no. 1119: E. tubiflorum Benth., Patzcuaro, Oct. 17, 1898, no. 3007, Oct. 19, 1898, no. 3232, Oct. 10, 1899, no. 3600: E. glabratum HBK., Pachuca, Oct. 28, 1903, no. 5255; Amecameca, Oct. 22, 1903, no. 5204: E. trinervium Schz. Bip., Oaxaca, Nov. 14, 1903, no. 5418: E. Gonzalezii Rob., Etla, State of Oaxaca, Nov. 13, 1903, no. 5403: Eupatorium sp., Cuernavaca, Sept. 26, 1898, no. 3013; Patzcuaro, Oct. 17, 1898, no. 3100: Stevia rhombifolia HBK., Jalapa, Oct. 2, 1898, no. 3107; Pachuca, Oct. 5, 1899, no. 3581, also Sept. 1, 1903, no. 6724 (Rose & Painter): Ageratum corymbosum Zacc., Yautepec, Oct. 23, 1903, no. 5235; Cuernavaca, Sept. 28, 1899, no. 3509: A. strictum Cuernavaca, Sept. 30, 1899, no. 3533.

The uredospores and teleutospores of this species closely resemble those of Puccinia Conoclinii, but are noticeably larger.

41. PUCCINIA DESMANTHODII Diet. and Holw.

On Desmanthodium fruticosum Greenm., Oct. 9, 1903, no. 5130: D. ovatum Benth., Etla, State of Oaxaca, Nov. 13, 1903, no. 5402.

42. Puccinia paupercula, n. sp.-Teleutosori hypophyllous, crowded in orbicular groups, 1-4mm across, minute, punctiform, confluent, soon naked, compact, chocolate-brown, usually cinereous by germination; teleutospores oblong or lance-oblong, 15-17 by 39-50μ, acute or obtuse at apex, obtuse or narrowed at base, slightly or not constricted at septum, wall smooth, rather thin, thicker at apex, 7-9 μ; pedicel colored like the spore, firm, one half length of spore or less.

On Elephantopus spicatus Juss., Veracruz, Oct. 5, 1898, no. 3074.

This species differs from Puccinia Elephantopodis P. Henn., from Argentine, by the position and arrangement of the sori, as well as in the shape and size of the spores.

43.

PUCCINIA ABRUPTA Diet. and Holw.

On Viguiera excelsa Benth. & Hook., City of Mexico, Oct. 18, 1903, no 5174; Amecameca, Oct. 20, 1903, no. 5197: V. tenuis A. Gr., Guadalajara,

Sept. 30, 1903, no. 5079: V. helianthoides HBK., Santa Fé, near City of Mexico, Oct. 18, 1903, no. 5173; Tehuacan, Nov. 8, 1903, no. 5358: V. buddleiformis Benth. & Hook. f., Patzcuaro, Oct. 20. 1898, no. 3217, Oct. 13, 1899, no. 3630; Rio Hondo near City of Mexico, Oct. 4, 1899, no. 3563; Morelia, Oct. 14, 1899, no. 3634: Viguiera sp., Guadalajara, Sept. 29, 1903, no. 5070.

The teleutospores on each species of host differ a little from all the others. It would be possible to make as many species of rusts as there are species of Viguiera, but the differences are of a character that can very plausibly be ascribed to the influence of the host, and it seems more in keeping with the present conception of species, therefore, to list these slight variations, whose limits are yet undetermined, under a single name. The specimens cited, therefore, include what have been separated as Puccinia abrupta D. & H. and P. subglobosa D. & H. An examination of the type material of P. Viguierae Peck, discloses the fact that the host was incorrectly determined by the collector. The rust is clearly not one of the forms on Viguiera, but is doubtless P. Helianthi Schw.

44. PUCCINIA NANOMITRA Syd.

On Viguiera eriophora Greenm., Oaxaca, Oct. 21, 1899, no. 3689: V. dentata Spreng., Oaxaca, Oct. 25, 1899, no. 3744.

45. PUCCINIA IOSTEPHANES Diet. and Holw.

On Iostephane heterophylla Benth., Cuernavaca, Oct. 30, 1903, no. 5291. 46. PUCCINIA COGNATA Syd.

On Verbesina tetraptera A. Gr., City of Mexico, Oct. 11, 1898, no. 3061; Rio Hondo, near City of Mexico, Oct. 4, 1899, no. 3564; Patzcuaro, Oct. 13, 1899, no. 3627; Oaxaca, Oct. 21, 1899, no. 3706: V. pinnatifida Cav., Cuernavaca, Nov. 1, 1953, no. 5307: V. sphaerocephala A. Gr., Zapotlan, State of Jalisco Oct. 9, 1903, no. 5141: V. montanoifolia Rob. & Greenm., Patzcuaro, Oct. 16, 1898, no. 3000, Oct. 10, 1899, nos. 3605, 3606; Morelia, Oct. 8, 1899, no. 3592.

The collection on V. sphaerocephala is without teleutospores, and is referred here with some slight doubt, as the uredospores of several related species are much alike. In deciding upon the boundaries of this species it has not been possible to agree with SYDOW in his Monographia Uredinearum. The Schweinitzian species, which is founded upon a South Carolina collection, probably on Verbesina occidentalis, although the specific determination was not made at the time, appears to be confined to southeastern United States, and is not yet reported on any other host than V. occidentalis. The species named by LONG Puccinia similis, and changed by SYDOW to P. cognata, occurs from Texas southward, upon a variety of hosts. It may be identical with the South American P. Spegazziniana DeT., but the exact proof is not at hand. The form on P. montanoifolia has slightly smaller and paler spores, but otherwise the same. No. 3606 is accompanied by an abundance of aecidia.

47. PUCCINIA FEROX Diet. and Holw.

On Verbesina diversifolia DC., Oaxaca, Oct. 21, 1899, no. 3692; Etla, Oaxaca, Nov. 14, 1903, no. 5396.

48. PUCCINIA AFFINIS Syd.

On Verbesina trilobata Rob. & Greenm., Oaxaca, Nov. 15, 1903, no. 5420: Verbesina sp., Etzatlan, State of Jalisco, Oct. 2, 1903, no. 5093.

49. PUCCINIA TUBERCULANS E. and E.

On Aplopappus spinulosus DC., Aguas Calientes, Sept. 12, 1899, no. 3404: Bigelovia veneta A. Gr., Pachuca, Oct. 27, 1903, no. 5250, Oct. 5, 1899, no. 3584.

50. PUCCINIA PRAEMORSA Diet. and Holw.

On Brickellia veronicaefolia A. Gr., Tehuacan, Nov. 7, 1903, no. 5343.

51. PUCCINIA DECORA Diet.

On Brickellia megalodonta Greenm., Guadalajara, Sept. 22, 1903, no. 5022.

52. PUCCINIA INVESTITA Schw.

On Gnaphalium semiamplexicaule DC., Santa Fé, near City of Mexico, Oct. 13, 1903, no. 5175; Amecameca, Oct. 20, 1903, no. 5191: G. leptophyllum DC., Nevada de Toluca, Oct. 15, 1903, no. 5155: G. oxyphyllum DC., Amecameca, Oct. 20, 1903, no. 5194: Gnaphalium sp., Oaxaca, Nov. 11, 1903, no. 5381.

53. PUCCINIA EVADENS Harkn.

On Baccharis glutinosa Pers., Etla, State of Oaxaca, Nov. 13, 1903, no. 5409: B. pteronicoides DC., Patzcuaro, Oct. 14, 1898, no. 3099: Baccharis sp., City of Mexico, Sept. 20, 1896.

54. PUCCINIA BACCHARIDIS-MULTIFLORAE Diet. and Holw.

On Baccharis multiflora HBK., Santa Fé, near City of Mexico, Oct. 18, 1903, no. 5166; Amecameca, Nov. 20, 1903, no. 5430: B. elegans HBK., Oaxaca, Nov. 11, 1903, no. 5382.

PURDUE UNIVERSITY,

Lafayette, Ind.

A MORPHOLOGICAL STUDY OF ULMUS AMERICANA.

CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY.

LXXVIII.

CHARLES H. SHATTUCK.

(WITH PLATES VII-IX)

A STUDY of this species was suggested by the interesting results of recent investigations in this region of the Archichlamydeae; notably those of KARSTEN (12), Miss BENSON (1), ZINGER (22), and NAWASCHIN (16).

METHODS.

Collections were made from February 13 to May 1, 1903, and repeated during the same period for 1904. During the first year collections were made on alternate days throughout the more rapid period of growth, and at intervals of ten days at other times. During the second year the same plan was followed except that collections were made every day during the period of fertilization and embryo growth.

The ovules are covered with a dense growth of hair which prevents sinking in the killing fluid; but after immersion in 95 per cent. alcohol they sink at once. A 2 per cent. solution of chromoacetic acid was found to give the best results as a killing agent for all but the oldest stages; these requiring a somewhat stronger solution.

The material was imbedded in paraffin and the sections were cut from 2 to 10μ in thickness. A preparation of Le Page's glue and glycerin was used for fixing sections to the slide (glue 40 parts, water 10 parts, glycerin 50 parts). The albumen and several other fixatives were first tried, but all failed to fix the sections to the slide. The glue mixture is as perfectly transparent on the slide as Mayer's albumen fixative, is more easily prepared, is a much stronger adhesive, will keep indefinitely, and is not so easily coagulated by heat.

The most satisfactory combination for staining the ovules was found to be safranin and gentian violet. The addition of orange G to the above brought out the pollen tubes best, as they hold the gen1905]

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tian violet after it is drawn from the nucellus and integuments. The male cells stained best in orange G. Haidenhain's iron-haematoxylin gave good results, as did also gentian violet.

FLOWERS.

The earliest stages in the development of the flower were not studied. The first collecting was done on February 13, when the ovule was found to contain a clearly defined megaspore, and the anthers to be in the pollen mother cell stage. By March 25 the trees were in full bloom.

The method by which self-pollination is prevented, at least to a large extent, is of interest. When the flower bud first opens, the two-parted stigma is found protruding beyond the anthers and is ready for pollination (fig. 1). About two of the more centrally placed flowers in each cluster are somewhat earlier than the others in lengthening their flower stalks and filaments and in opening their anthers (fig. 2). The first flower to open its anthers has an excellent opportunity to pollinate the entire cluster. At the same time this flower may be prevented from self-pollination only by the pollen from some earlier flower having reached its exposed stigma before its own anthers were opened. In many instances the stigmas of flowers whose anthers were not yet open were found covered with pollen grains, some of which had developed tubes. As the time requi ed for the pollen tube to complete its growth is from one to three days, it is quite evident that these early tubes will have completed the act of fertilization in each flower before its own pollen grains have an opportunity to begin the development of tubes.

MICROSPORANGIUM.

On February 13 the microsporangia were well formed. Most of the sporogenous cells of the four chambers were in the spore mother cell stage, in which they had evidently passed the winter (fig. 3).

It is of interest to note that at this stage it is impossible to distinguish any definitely organized tapetum, the cells all having the same size and shape, and giving the same reaction to stains. Sporangia of the same date were found in which the mother cells had passed into the synapsis stage (fig. 4); the nucleolus staining red and the chromatin mass violet. Many of the cells which were functioning