180 



Empetraceae. 



Empetrum. Crowberry. 

 (Family Empetraceae). 



Low spreading shrubs with ex- 

 foliating bark: evergreen. Twigs 

 slender, ridged below the leaf- 

 scars: pith minute, continuous. 

 Buds solitary, sessile, compressed 

 round-ovoid, with 2 or 3 exposed 

 scales, very minute except for the 

 flower-buds in the upper axils. 

 Leaf-scars subverticillate, minute, 

 half-round, somewhat raised: 

 bundle-trace 1, indistinct: stipule- 

 scars lacking. Leaves small, el- 

 liptical-oblong, revolute to a hairy 

 groove, entire. 



The winter-characters of Em- 

 petrum nigrum are given by 

 Bosemann, 35; and Fant, 53. 

 Solereder figures a cross-section 

 of its leaf in his Systematic Anat- 

 omy of the Dicotyledons, 2:800, 

 f. 188. 

 The type of inrolled leaves that Empetraceae and certain 

 Ericaceae possess has been shown by Gibelli's developmental 

 studies to differ essentially from the usual type of revolute 

 leaves which are merely rolled backward for a distance from 

 the margin. Here, the grooves at either side of the midrib 

 develop in such a manner as to make them morphologically 

 elongated pits rather than merely covered parts of the nor- 

 mal lower leaf surface. 



Glabrate. E. nigrum. 



Tomentose. E. nigrum andinum. 



