26 i'HP:slUh'NT'.S ADDRE.<S. 



jiliyllodiuiii oi- (lilattMl j)cliiilc" (Fl. Aiist., ii.. p. 301). Kciiut says* — "It lias 

 already been mentioiieil on p. 335 [(|Uoteii later on t'oi another reason] that a 

 like nioditieation of function oeeurs in many Australian Aeaeias, the foliage- 

 leaves of whieli are de\oid of green blades whilst the leaf stalks are developed as 

 gi'een, flattened, outspread organs, the so-called phyllodes." These, and similar 

 statements are based on no more logical argument than this — The phyllodiiieous 

 Acacias have phyllodes; phyllodes are flattened petioles, &c.; therefore the idiyl- 

 lodes of Acacias are flattened petioles, which have lost iheir l)lades. The fallacy 

 of the argument lies in the fact, that the so-called |)lyil(MUneous Acacias have 

 not i)hyllodcs in the accei)ted meaning of the term. 



Sometimes however, authors venture to give an explanation. Hut the ex- 

 planations known to me are not less fallacious than the definitions of the phyl- 

 lodes, so-called, of Australian Acacias. For example, Lubbock, in his "Flowers, 

 Fiuit.s, and Leaves" (p. 120, %. 75: 1880) gives an explanation, together with 

 an illustration of a seedling — the liret ever )niblished, as far as 1 know, lie 

 says — "The ly])ical leaves of Acacias are pinnate, with a numbei- of leaflets. 

 On the other liand, many of the Australian Acacias have leaves (or. to sjieak more 

 correctly, jihyllodes) more or less elongated or willow-like. But if we raise 

 them from seed we tind, for'instance. in Acacia mlicina, so called from its le- 

 semlilance to a Willow, that the lirst leaves are pinnate (Fig. 75), and ditlVr 

 in nothing from those characteristic of the genus. In the later ones, however, 

 the leaflets are I'educed in number, and the leafstalk is slightly compressed 

 laterally. The fifth or sixth leaf, perhaps, will have the leaflets reduced to a 

 single )iair, and the leaf-stalk still more flattened, wliilc when the jilant is a little 

 older, nothing remains excejit the flattened ]>etiole." Xow the passage (juoted is 

 very remarkable, liul hardly more so than others of similar import to be found 

 in <ither books. Such statements are im|)erfect generalisations baseil upon in- 

 ade(|uate niateilal. Though jiiit forward in good I'aith, they are nevertheless 

 pitfalls and stumbling-lilocks. lioth for teachers and students. The first state- 

 ment that "the tyi)ical leaves of Acacias are pinnate" is faulty. There are no 

 Acacias with jiinnate leaves. On the contrary, the typical Acacias have twice 

 ))innate or bi])innate leaves. Xext, "I'lit it we raise them from seed we fliul, 

 for instance, in Acacia saliciiui . . . that the Hrst leaves are pinnate (Fig. 

 75), and differ in nothing from those characteristic of the genus." The seedling 

 shown in Fig. 75 has no pinnate leaf or leaves. The first is a liipinnate leaf 

 with one jjair of pinn;B, the second is also a bipinnate leaf with one i)air of 

 jiinnie. and with an indication of the so-called phyllode on the ii])per .side: the 

 third is also l)ipinijate with one ])air of inniia'. and indications of the so-called 

 ))liyllo<le on both upper iind lower siilcs; while the luurlli niiil fifth are complete 

 phyllodes. so-called. 



Lulibock's descrii)tion and figure of a seedling of .1. saliciiia are the mdv 

 ones of this s))ecies yet iiublished. But if the seedling figured was not an 

 anomalous (jiie, it was an incomplete specimen; and Lubbock ilid not notice that 

 the first leaf, which should have been a simply pinnate leaf, or i)erhai)s a pair 

 of opposite simiily pinnate leaves, was missing. But what one particularly 

 wants to know, is. why Lubbock calls the structure, to which the single pair of 

 jiinna' of his bipinnate leaves is attached, the "leaf-stalk," which is firstly slightly 

 compressed laterally, and then finally become the flattened petiole or phyllode? 

 Tn other words, on what gTounds is it taken for granted that the iiinna? of the 



'Natural History of Plants, En<;lish TiT.nslation, Vol. i.. |i.ii:f7. 



