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///C--JW- 'j-riyrv Acumination, see acumen and acuminate. 



A'^gpOu^M Alar cells, the cells at the basal angles of 



|\UQU^f.||J[|j| the leaf, commonly different from the cells of 

 ))y^ra,^7)fllli^ the main part of the leaf, being shorter and 

 often nearly square, or inflated and hyaline, 

 and often highly colored. (Fig. I.) 



Apical cells, the cells composing the apex 

 of the leaf. They are often broader and shorter 

 1 than the cells of the middle of the leaf. 



Areolalion, the net-work formed by the outlines of the cells 

 of a leaf. 



Auricles, small lobes at the basal angles of 

 the leaf, usually consisting of cells differing 

 from those of the main part of the leaf in size 

 or shape or both. (Fig. i and Fig. 2, a.) Prop- 

 erly used only when there is an outward curve 

 in the outline of the leaf at the base, as in the 

 figures, but often used loosely to denote the 

 basal angles of widely decurrent leaves. 



Basal or basilar cells, cells at the base or 

 insertion of the leaf, often of different shape 

 and color from those of the main part of the leaf. 

 Bicostate, having a double costa, which is usually 

 much shorter than in leaves having a single costa. 

 Bifarious, growing in two ranks. 



Bracts, a term applied to the leaves surrounding 

 the reproductive organs. Those surrounding the anthe- 

 ridia are called perigonial bracts or leaves, and those sur- 

 rounding the archegonia and base of seta are called 

 perichaetial. 



Bistratose, of two layers of cells. (Fig. 3.) 

 Canaliculate, channelled. Applied to leaves with margins 

 incurved, so as to give them a channel-like form, e. g. the upper 

 part of the leaves of Dicranum fuscescens. A 

 more complete inrolling until the margins meet 

 would make the leaf tubulose. 



Bordered, having a margin different from 

 the rest of the leaf. In Mnium and Bryum the 

 border consists of a few rows of greatly elon- 

 gated cells, often in two or more layers. In 

 Fissidens the border is of a different color, but 

 with little difference in cell structure. (Fig. 4.) 

 (To be continued.) 



SB 



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