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Anatomy of Two Mechanisms of Breaking Physical Dormancy by Experimental Treatments in Seeds of Two North American Rhus Species (Anacardiaceae)

Xiaojie Li, Jerry M. Baskin and Carol C. Baskin
American Journal of Botany
Vol. 86, No. 11 (Nov., 1999), pp. 1505-1511
Stable URL: http://www.jstor.org/stable/2656788
Page Count: 7
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Anatomy of Two Mechanisms of Breaking Physical Dormancy by Experimental Treatments in Seeds of Two North American Rhus Species (Anacardiaceae)
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Abstract

Anatomy of the endocarp was studied in relation to the physical dormancy-breaking mechanisms in experimentally treated Rhus aromatica var. aromatica and R. glabra germination units, which include seed plus endocarp (hereafter seeds). The endocarp has three distinct layers, with brachysclereids on the outside, osteosclereids in the middle, and macrosclereids on the inside. Brachysclereids in the carpellary micropyle region (i.e., region immediately adjacent to the integumentary micropyle) are shorter than those in other parts of the endocarp, and the macrosclereids in this region are not elongated. Thus, a weak point is formed in the endocarp. Concentrated sulfuric acid broke seed dormancy in R. aromatica by eroding the brachysclereids and osteosclereids in the carpellary micropyle region, whereas boiling water broke dormancy in seeds of R. glabra by inducing a blister adjacent to the carpellary micropyle.

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