100 ROBERT TRACY JACKSON OX 



axils of older leaves, the leaves are also trilobed, with an elongate, median lobe, as in the 

 seedling. In Acer sjjicatiim Mr. Deane ('96) observes that, " The leaves on the ends of 

 new shoots in the old plants resemble in shape and size the first leaves of the seedling." 

 This and many other facts are shown in Mr. Deane's very interesting collection of seedlings. 

 Elongate weakly trilobed leaves on terminal shoots, similar to the seedling, also occur in 

 the White Maple (Acer saccharinum L.), Moose-wood (^Acer pennsylvanicu77i), and 

 Norway Maple (Acer platanoicles) . In the Moose-wood the leaves may even be entire, 

 as noted in the young seedling of that species. 



Acer platanoides. In Acer platmioides the leaves are palraately five-lobed, but 

 seedlings closely resemble the seedlings of the Red Maple. Suckers froin a stump of this 

 species (PI. 18, fig. 34) at tlie Ijase, had trilobed leaves wuth an elongate median lobe, as 

 in the young. The succeeding leaves, however, were palmately five-lobed, nearly or 

 quite as in the adult. Similar trilobed leaves occur in suckers at the base of the White 

 Maple (^Acer saccharinum). 



Chinese and Japanese Maples. In China and Japan there is a very interesting series 

 of primitive types of maples, for the opportunity of studying which I am indebted to the 

 Arnold arboretum. 



Acer oblongum Wall., from the Province of Hu-Peh, China, Coll. Dr. Aug. Henry. 

 In this species the leaves (PI. 17, fig. 30) are elongate, oval, acuminate, margins entire. 

 It would hardly, if at all, be recognized as belonging to this genus, were it not for the 

 fruit. Besides the median vein, two strong lateral veins diverge from the base, as is 

 usual in maples. All the evidence of palaeontology and ontogeny shows that entire 

 leaves are more primitive than dentate or lobed leaves. Therefore we may properly 

 consider this as an extremely primitive type, in fact structurally more primitive than 

 any other known living or fossil species of maple. It is also more primitive structurally 

 than the known seedling maples. 



Acer carpinifoJlum S. and Z., from Nikko, Japan, Coll. Prof. C. S. Sargent, is 

 another very striking type. The leaves (PI. 17, fig. 31) are elongate, oval, acuminate, 

 with serrate margins. The leaves at the end of the branch have slight marginal 

 undulations about 15 mm. from the base, as in the figure. Leaves situated nearer 

 the base of the branch do not show these undulations, but are slightly inequilateral. 

 The veins are given off obliquely from the midrib and are parallel to one another, 

 no strongly marked lateral veins existing, as in Acer oblongum. This species may be 

 considered as structurally more specialized than Acer oblongum on account of its 

 dentate margins. 



Acer crataegifoUum S. and Z., from Nikko, Japan, Coll. Prof. C. S. Sargent, is an 

 interesting type. The leaves (PL 17, fig. 32) are broadly oval and slightly dentate, two 



