114 PvODERT TRACY JACKSON ON 



clothed with the nopioiiic or pnmary leaves. These leaves (PI. 21, fig. 73) are linear, 

 acuminate distally, flattened on the inner aspect and curved on the outer (Fig. 73a). On 

 the borders or edges are two rows of delicate saw-like s^iines, pointing distally. No third 

 row exists as in adult leaves. From about 13 to 20 mm. above the cotyledons the bundles 

 of leaves typical of the species begin to appear in the axils of the primary leaves (PI. 21, 

 fig. 74). These bundles of leaves are usually in threes, but clusters are found in which 

 two leaves occur instead of three ; they are not very common, however. The first two or 

 three primary leaves which bear axillary clusters of needles (PL 21, fig. 74a) are long and 

 acicular, as are preceding primary leaves. Succeetling primary leaves, however, rapidly 

 shorten, while retaining the leafy character ; Init within a short distance are reduced and 

 represented only by rather prominent scales (PI. 21, fig. 75), which subtend the leaf- 

 clusters. During siicceeding growth to the adult, scales normally occupy the same 

 position at the base of leaf-clusters. 



In the adult Pitch Pine the leaf-clusters are composed of three leaves, Ijasally sur- 

 rounded by a sheath (PI. 21, fig. 75) . From their packed condition during gx-owth each 

 leaf has assumed a form roughly triangular in section, ))ut curved on the outer side. On 

 the three edges (two lateral and one median) a series of fine saw-like serrations have 

 developed similar to those seen in primaiy and secondary leaves of other pines. Mr. 

 Charles E. Faxon informs me that lie has seen a branch of this species in which all the 

 leaves were in bundles of fives. As five leaves may be considered more specialized than 

 three leaves, the typical condition in this species, such a branch may properly Ije consid- 

 ered a progressive localized variation. 



When a young Pitch Pine has lost its leader or other prominent shoot, or, according 

 to Emerson ('46) and Sargent ('91-97), on stum23s or after fire, a secondary sucker-like 

 growth may be induced. These secondary growths are commonly vigorous (PI. 21, fig. 76 

 and fig. 77), and the scales have taken on a leafy expansion. The leaves are long, 

 acuminate distally, flattened on the inner and curved on the outer side ; also they bear a 

 row of saw-like teeth on the edges. They are thus seen to be closely similar to the 

 nepionic primary leaves. These reversionary or localized primary leaves usually bear a 

 bundle of leaves in their axils (PI. 21, fig. 70), but the l)undles in some cases may not 

 develop, as shown in a few leaves in the figure. Raj^id growths from the stump may be 

 entirely composed of primary leaves (PI. 21. fig. 77). the bundles not developing until 

 later. Emerson ('46) says of the Pitch Pine, " Its stump throws up sprouts the spring 

 after the stem has been felled. * * * The fallen trunk itself thi-ows out sprouts in the suc- 

 ceeding summer ; and the Ijundles of leaves of both are remarkable for issuing from the 

 axil of a single leaf, in the same manner as is observed in the young plant." 1 liave occa- 

 sionally seen in a very Umited way similar growths on adult trees, where no apparent 



