315 



Decurrence of Leaf. 



When the green tissues of sessile leaf blades is continued down the stem, by 

 adhesion, in the form of two green bands or wings, the leaf is said to be decurrent. 



A marked case is rare in Eucalyptus. We have it in E. Floclctonice, figs. 3a 

 to 3c, Plate 236, Part LVIII, which is the best example known to me. It occurs also 

 in E. macrocarpa, fig. la, Plate 77, Part XVIII. 



The typical form is morphologically close to " stem-clasping," and less close 

 to that extreme form of quadrangularity which exhibits that type of winged stem 

 which is familiar to us in E. quadrangulata and E. tetragona. In the latter species it 

 is not the lobes of the leaf (or of two opposite leaves) which are concerned, but one 

 (or two) flattened or expanded petioles, with no lamina. 



Angularity of Branehlets. 



A few notes may be required on some of the minor characters which I have made use of or 

 neglected in the specific diagnosis and descriptions. I have thought it generally useless to describe the 

 branehlets terete or angular, for in those species such as E. pruinosa, E. tetragona, E. tetraptera, kc, where 

 the angles are often so prominent as to be almost transformed into wings, there occur branches, often on 

 the same specimen, quite terete. (B.F1. iii, 186.) 



For sketches of angular stems of these species, see' E. pruinosa (Part XII, 

 Plate 51) ; E. tetragona (Part XL VI, Plate 188) ; E. tetraptera (Part XXII, Plate 94). 

 An exaggerated case is that of E. quadrangulata, of which a section of the young stem 

 is figured at fig. 4e, Plate 103, Part XXIV. 



It is probably the case that some branehlets will be found to be angular in all 

 species. The following are some in which I have personally observed to be marked, 

 in addition to those mentioned by Bentham, and I could mention others. 



E. globulus and its allies.— Z?. Maideni, E. unialata, and E. goniocalyx. 



E. tereticornis and its allies. — E. rostrata and E. amplifolia. 



E. eosinophylic. E. Planchoniana. 



E. dumosa. E. Preissiana. 



E. Kybeanensis. E. propinqua. 



E. macrocarpa. E. punctata. 



E. neglecta. E. Shirley i. 



E. nitens. E. Woodivardi. 



In a note " On the forms of Stems of Plants " (British Association Meeting, 

 22nd August, 1901), Lord Avebury remarks : " Plants with quadrangular stems always 

 have opposite leaves." He was referring to such families as the Labiatse, but it is true 

 of many Eucalypts, so far as the juvenile foliage is concerned. 



