1915] FARR—INFLORESCENCES OF XANTHIUM 147 
modified is indicated by the observations of SCHWARZE, in that the 
cells of abortive stamens are often more vacuolate than those of 
stamens developing to maturity. 
LITERATURE CITED 
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eo 
i 
1897. 
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Kais. Acad. Wiss. Wien 116: 3-3 
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einiger Arten der Gruppe Ambrosieae und Stellung der letzteren in System. 
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14. SHULL, C. A., The oxygen minimum and germination in Noctinw seeds. 
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EXPLANATION OF PLATE X 
The figures were made with a camera lucida. The magnifications given 
abbreviations used are as follows: b, beaks; s, spines; 2, involucral bracts; /, 
floral bracts; a, abortive corolla; r, rudimentary floral bract; p, pistillate 
head; c, carpels; 1, leaf; w, pistillate flower. 
