Leaf arrangement

Figure 8-12. (a) The scattered leaf arrangement (phyllotaxis) of Plantago media (drawing by Ferenc Lantos, Pecs). Fibonacci numbers of spirals in the patterns of (b) Scales of a pinecone and (c) A cactus in Hawaii (b and c, photographs by the authors). 

Phyllotaxy.—Phyllotaxy is the study of leaf arrangement upon the stem or branch, and this may be either alternate, opposite, whorled, or verticillate, or fascicled. It is a general law in the arrangement of leaves and of all other plant appendages that they are spirally disposed, or on a line which winds around the axis like the thread of a screw. The spiral line is formed by the union of... 

Figure 8-12. The scattered leaf arrangement (phyllotaxis) of Phntago media.

FIGURE 4.2 Leaf arrangement in Cyathophorum bulbosum (Hedw.) MUll. Hal. (ventral view). Epiphytic plant from densely shaded, living roots of a tree near a streamlet in remnant of native forest, White Pine Bush, Hawke s Bay, North Island, New Zealand Van Zanten 73.12.68, GRO). (Photograph courtesy and by permission... 

Considering in more detail the species descriptions in Fig 11.3, these were designed to be as brief as possible, and to focus upon sterile diagnostic characters, particularly those not visible in the illustration, such as colour, slash, smell and bole diameter. Certain key characters - bole diameter, habitat, leaf arrangement (alternate or opposite) and leaf structure (simple or compound) - are shown for every species. The remainder of the characters comprise those that are useful for distinguishing the species, which therefore differ between groups. 

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