

276 



DR. M. T. MASTERS ON THE MORPHOLOGY, 



If one of the lateral buds be examined at the same time, the 



axis 



margins the leaves protrude, those at the upper edge of the cup 

 being the oldest and corresponding to those at the base of the 

 dome. These lateral buds are those destined to form the tufts 

 of leaves on the spurs. The greatest energy of growth is in the 

 one case at the apex of the growing axis, in the other at the 

 base. 







Cladodes or Phylloclades. 



The peculiar flattened, often lobed and branching expansions 

 in the genus Phyllocladus originate in the axils of scale-like 

 perulse or of linear primordial leaves similar to what may be ob- 

 served on the seedling plant in succession to the cotyledons. 

 Their position and anatomical structure leave no doubt as to their 

 true morphological nature as branches of a peculiar character. 



The leaves are concrescent with the cladode, and their arrange- 

 ment is described by Van Tieghem as distichous, concrescent 

 with each other in each row and with the branch, so as to form 

 with it a single flattened branch toothed at the edges. In the 



upper part the cladodia are arranged spirally in more than one 

 plane. 



The fact of a branch originating from the axil of a rudimentary 

 leaf, producing a green leaf or a small number of green leaves 

 and then ceasing to grow, is compared by Van Tieghem to what 

 takes place in Sciadopitys *, wherein the leaves are inseparate or 

 concrescent and form a single blade or needle, which has its 

 dorsal surface (phloem) upwards and its ventral or xylem surface 

 beneath. 



''Needles" q/* Sciadopitys— Functionally these structures are 

 leaves, morphologically they present greater resemblance to axial 

 structures. They occupy the axils of leaves of the first order, 

 and thus correspond in position with the fascicle of leaves in 

 Pinus or the seed-scale in the cones of Abietinere. 



If examined in the bud-stage, each appears as a tubercle notched 

 at the apex and placed in the axil of a perula which is clearly 

 homologous with a leaf. After the formation of the notch at the 

 apex no further growth in that situation occurs, subsequent 

 increase taking place by intercalary additions at the base. The 



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* See Van Tieghem, Traite de Botanique, p. 1321. 



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