PRESIDENT S ADDRESS. -3 



short, bipiimatc loaves, with several, or only one pair of pinnse, whose pinnae 

 have vanished. Tlierel'ore, as the so-called phyllodes of the Australian phyllo- 

 dineous Aeaeias are not e.xaetly eomparable with the phyllodes of other plants, 

 and are not phyllodes witliin the meaning of the current definitions thereof, they 

 should be distinguished from ordinary phyllodes, and also have a distinctive name. 

 As they are neither cladodes nor phylloclades, within the meaning of the current 

 definitions of these stru<;tures, I propose to call them Euphyllodia or euphyllodes, 

 in tlie sense that they are something more than is implied in the accepted defini- 

 tion of phyllodes; and. therefore, something more than simply flattened i^etioles; 

 inasmuch as they really are. as 1 shall show, in what follows, vertically flattened, 

 primary leaf-axes or common petioles, whose pinna? have been suppressed, which 

 have usurped the form and function of lea\es. Instead of Phyllodinea! and 

 phyllodineous Acacias. T propose to use the terms Eupliyllodines and euphyllo- 

 dineous Acacias, in order to be consistent. 



Several more detailed interpretations of the phyllodes. so-called, of Aus- 

 tralian Acacias are on record. One was offered by Morren. in 1852.* Unfor- 

 tunately, no copy of this paper is available in Sydney, and I do not know on 

 what kind of evidence he based his views. But two authore, Maxwell Masters 

 and Baron von Mueller, have given the substance of Morren 's hypothesis. Mas- 

 ters says§ — "When the blade of the leaf is suppressed it often happens that 

 the stalk of the leaf is flattened, as it were, by cimipensation, and the petiole 

 has then much the appearance of a flat ribbon (phyllode). This happens con- 

 stantly in certain species of Acacia, Oxalis, &c.. and has been attributed, but 

 doubtless erroneously, to the fusion of the leaflets in im early state of develop- 

 ment and in the position of rest." 



Baron von Mueller seems to have acceiited Morren's hypothesis, but without 

 mentioning the author of it. In his "Introduction to Botanic Teachings" (p. 

 25. 1877), he says of the Australian Acacias — "This enormous number of con- 

 generic plants [about .300 species] can conveniently be separated into two main 

 groups, according to the structure of their leaves, whetiier consisting of a simple 

 blade, or whether formed by distinct leaflets. The first of this primary division 

 is called that of the Phyllodineje, from a Greek word implying leaf-like form, 

 because the supposed simple leaves are in reality formed by the confluence of 

 leaflets, stalldets and stalks into one leaf-like mass, or according to the more 

 generally adopted but less accurate views simply dilated leaf-stalks (piiyllodia ) ; 

 this metamorphosis is most readily demonstrated and proved by observing the 

 apparently simple-leaved Acacias in early growth, when the first leaves developed 

 by the young seedling will be found to be compound, consisting of leaflets ar- 

 ranged in two rows, thus forming iiinnae, several again of these pinn<B forming 

 the bipinnate leaf, the axes along which the leaflets are placed being also ar- 

 ranged in a pinnate manner. What in the phyllodineous division of the genus 

 Acacia is noticed only on the leaves of the young plant, becomes normal through- 

 out for the second group, that of the Bipinnatse." 



A second interpretation is current in Textbooks of Botany. This is not 

 less unsatisfactory than the Baron's. It is frequently presented as a brief, 

 definite, and apparently authoritative statement — an axiom or a postulate, as it 

 were, which the student is to accept in faith. For example. Bentliam, in his 

 generic description of Acacia, says — "Leaves twice pinnate or reduced to a simple 



•0. Morren, Bull. Acad. Beltf., 18.52, t.xix., p. 444. 

 SMasters, Vegetal)Ip Teratology, p.329, 18(i9. 



