Stem leaf, orientation

Many studies have been reported on extractability and concentration of protein from leafy plants (13, 14). While it is more efficient to consume the leafy vegetable or fruit directly, considerable quantities of less available protein can be made available through extraction and concentration into LPC. As pointed out by Pirie (13) and Kohler Knuckles (14), an LPC processing plant could be oriented near packinghouses for leafy vegetables so that leaves, stems, and stalks trimmed from these vegetables before being sent to market, could subsequently be extracted for protein. Leaf protein processes are covered in more detail in another chapter. 

Mayne, Thomas, and others (38, 60, 81) have observed in the Orient that active defoliation from coffee leaf rust will leave unhealed places at the points where unseasonably dropped leaves were attached to stems. Into the leaf traces left exposed Colletotrichum and similar weakly parasitic organisms will enter and cause dieback. Many gross observations in the western tropics on chronic deterioration, paralleling... 

FIGURE 4.5 Leaf and stem trichomes (A) adaxial surface, falcate and moniliform trichomes pointing toward the leaf apex (B) abaxial surface displaying falcate, moniliform, and glandular trichomes, the orientation of which is more random (C) glandular trichome found only on the abaxial surface (D) falcate and moniliform trichomes and (E) acuminate trichomes on an immature stem. 

For leaves of dicots, stomata are usually more numerous on the lower (abaxial) surface than on the upper (adaxial) one. In many dicots, stomata may even be nearly absent from the upper epidermis. On the other hand, many monocots and certain other plants with vertically oriented leaves have approximately equal numbers of stomata per unit area on each side. A frequency of 50 to 300 stomata per mm2 is representative for the lower surface of leaves of most mesophytes stomatal frequencies for leaves and photosynthetic stems of xerophytes are usually 20 to 80 per mm2. The pores of the open stomata usually occupy 0.2 to 2% of the leaf surface area. Thus, the area for diffusion of gases through the stomatal pores in the upper or the lower epidermis of a leaf, Ast, is much less than is the leaf surface area, A. 

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