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Page number:512 
Remarks (internal):Species description based upon such representative cultures as NRRL 973 (Thom No. 4189) isolated from apples in 1917 by Drs. J. S. Cooley and Charles Brooks, Bureau of Plant Industry; NRRL 97G (Thom No. 4852) isolated from apples by Dr. Cooley in 1926; and NRRL 977 (Thom No. 4933.1) isolated by Professor F. D. Heald. Of six strains received in February 1946 from the Centraalbureau under the name Penicillium expansum, three (labelled "from Carica papaya," "No. 10b," and "No. 37," respectively) duplicate NRRL 973; the others (labelled "v. Luijk ?," "v. Luijk ?," and "No. 35") duplicate NRRL 97G. NRRL 979 (fig. 131C) cited in Thom's Monograph (1930, p. 412) as P. elongatum Dierckx from Professor A. W. Povah, as Thom's No. 5031.25, is regarded as representative of P. expansum (see p. 515).
Hundreds of strains belonging to this series have been isolated from naturally infected products. Workers in the fields of fruit storage and distribution find typical strains of Penicillium expansum to be the principal agent responsible for losses from storage rot. Coremia with white or more or less colored stalks and green heads composed of massed penicilli are abundantly observed on apples, pears, quinces and related fruits, also on grapes and cherries as they rot slowly in storage packages. Cultures from these penicillate heads produce the usual type of P. expansum already described, and conidia from these cultures regularly reproduce the rot found in. the stored product which carried its infection from the field to the storehouse. Corda described and figured such coremia (Prachtflora, p. 54, Pl. XXV. 1839) as representing his species Coremium vulgare. Cultures from many coremia, as collected, clearly show that if such heads consist of massed penicillate fruits, the conidia from them will grow in ordinary culture media as Penicillia in which the coremiform nature of the species is represented by the more or less definite fasciculation of the conidiophores. Only rarely are large coremia comparable to those seen on fruit reproduced in agar cultures.
In handling rotting fruit and other material showing moldiness, numerous mycologists in different laboratories and at different times have isolated and described, or described directly from natural substrata, various species which obviously represent the Penicillium expansum series. The number of species so described results both from the economic considerations underlying their isolation, and from the unusual prominence of these molds as they occur upon natural substrata in the form of yellow-green or glaucous, fasciculate or coremiform masses of fruiting structures. A partial list of such species follows while others are indicated among the synonyms of P. expansum Link already cited.
Description type:Non-original description 
Description:Penicillium expansum Link, emended in Observationes, p. 17. 1809; Thom, in U. S. Dept. Agr., Bur. Anim. Ind., Bul. 118, pp. 27-28, fig. 1. 1910. See also Thom, The Penicillia, pp. 402-405, figs. 60 and 61. 1930.
Synonyms: Coremium glaucum Link, in Observationes, p. 19. 1809.
Floccaria glauca Greville, in Scottish Flora, Pl. 301, figs. 1-4. 1823-1828.
Penicillium glaucum Link (in part), in Species Plantarum VI: 70. 1824.
Coremium vulgare Corda (in part), in Prachtflora, p. 54, Pl. XXV, figs. 3, 4, 17-21. 1839.
Colonies on Czapek's solution agar growing rapidly (fig. 131A), attaining a diameter of 4 to 5 cm. in 8 to 10 days at room temperature, with surface generally showing radial furrows, often ranging from 0.5 to 2.0 mm. deep, heavily sporing throughout with conidiophores very abundant and regularly arising from the substratum, in some strains occurring in an almost continuous dense stand (fig. 131A), in others showing some definite fascicles or clusters but with the majority of the conidiophores arising singly, in still other strains with conidiophores almost entirely grouped into fascicles or bundles with colony surface appearing "mealy" to granular, marginal area 1 to 2 mm. wide, generally white during the growing period, shading quickly to yellow-green shades near celandine or sage green (Ridgway, Pl. XLVII) with the ripening of conidia; limited exudate produced, mostly in small droplets, partially embedded in the conidial mass, colorless; odor strong, "moldy", characteristic of rotting apples; reverse almost colorless in some strains through yellow-brown to deep walnut brown in others. Conidial structures very abundant and, in mass, characterizing the colony. Conidiophores mostly 150 to 400 µm in length in some strains, but commonly up to 600 to 750 µm in others, mostly 3.0 to 3.5 µm in diameter with walls smooth or finely roughened, often appearing granular within, terminating in large penicilli commonly measuring up to 75 to 100 µm in length, bearing long, tangled chains of spores 150 to 200 µm in length (fig. 129A); penicilli asymmetric, commonly once or twice branched, with branches mostly 15 to 25 µm by 2.5 to 3.5 µm, occasionally up to 50 µm in length, typically appressed against the main axis with metulae arising from both at about the same level (fig.129B); metulae usually borne in verticils of 3 to 6 and measuring about 10 to 15 µm by 2.2 to 3.0 µm; sterigmata in groups of 5 to 8 or 9 and usually ranging from 8 to 12 µm by 2.0 to 2.5 µm, occasionally up to 15 to 16 µm by 3.0µm; conidia elliptical when first formed and usually continuing to show some ellipticity (fig. 129C), measuring mostly about 3.0 to 3.5 µm in diameter, in some strains becoming almost globose at maturity with walls smooth, appearing dull yellow-green in mass.
Colonies on steep agar growing more rapidly than. on Czapek, attaining a diameter of 5.5 to 6.0 cm. in 8 to 10 days, essentially as described above in pattern and texture; penicilli generally larger and conidia commonly showing greater irregularity in dimensions.
Colonies on malt agar attaining a diameter of about 5 cm. in 8 to 10 days, plane (fig. 131B), comparatively thin, with surface appearing definitely mealy or granular, occasionally developing definite and fairly conspicuous coremia; conidiophores as on Czapek but often appearing rough in the area just above the agar surface, with penicilli essentially as on Czapek but with spore chains commonly up to 350 µm in length.
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