In belladonna, stramonium, henbane, peppermint, spearmint, digitalis, and horehound, the outer wall of the epidermal cells is thin.
In witch-hazel, stramonium, coca, phytolacca, and peppermint there is a single layer of palisade parenchyma on the upper surface only of the leaf.
In senna there is one layer of palisade parenchyma on the upper and one layer on the under side of the leaf. In matico and tea leaves there are two layers of spongy parenchyma on the upper side of the leaf.
In chestnut leaves there are three layers of palisade parenchyma on the upper side of the leaf.
In eucalyptus leaves the entire central part of the leaf, with the exception of the secretion cells and fibro-vascular bundle, is made up of the palisade parenchyma.
In some leaves no palisade parenchyma occurs. Trailing arbutus (Plate 111) is an example of such a leaf.
In stramonium leaves the spongy parenchyma is strongly branched; in mountain laurel the spongy parenchyma is mostly non-branched and circular in form, as in trailing arbutus (Plate 111, Fig. 3), and as occurs in the midrib portion of most leaves.
PLATE 112
Powdered Insect Flower Leaves
(Chrysanthemum cinerariifolium [Trev.], Vis.)
1. Upper epidermis. 2. Under epidermis showing stoma and hair scar. 3. Cross-section of under epidermis with attached hair. 4. Cross-section of upper epidermis. 5. Hairs. 6. Mesophyll with chlorophyll bodies. 7. Conducting cells.