The morphology and relationships of the Monimiaceae

in these two genera needs to be verified by examination of more adequately preserved material.The ethereal oil cells, as noted by previous investigators, are formed in the mesophyll, and at times in the epidermis or hypodermis.Foliar hairs, when present, are unicellular except in the case of Amborella which forms both unicellular and multicellular trichomes, Bailey and Swamy (1).They occur singly, in small clusters of two, three or four, or in larger aggregates of tufted, fan-shaped, stellate or peltate forms.Although trichomes occur on the leaves of at least some species of all of the genera that we have studied, with the exception of X ymalos, Macrotorus, Macropeplus and Schrameckia, the types of hairs present vary greatly not only from tribe to tribe, but also within the same tribe and in certain cases within a genus or species.The anticlinal walls of the epidermal cells are straight except in Peumus, Piptocalyx, Glossocalyx and certain species of Trimenia and Kibara where they are more or less conspicuously wavy or undulating.The stomata are of two types: (1) '"syndetocheilic," viz.having subsidiary cells oriented parallel to the guard cells, and (2) "haplocheilic," viz.surrounded by ordinary epidermal cells.Stomata of the former type predominate in the Hortonieae, Trimenieae, Mollinedieae and Siparuneae, those of the latter type in the Laurelieae.The Monimieae are intermediate or transitional between "'syndetocheilic" and ''haplocheilic,' Tambourissa, Hennecartia and Schrameckia having stomata mostly of the former type, and Monimia and Palmeria those of the latter type.A one-, two-or three-layered hypodermis, composed of cells that commonly are distinctly larger than those of the epidermis, is characteristic of most genera with the exception of Piptocalyx, Matthaea, Daphnandra, Bracteanthus, Atherosperma and Glossocalyx.Palisade parenchyma usually is clearly differentiated except in Amdborella, Trimenia, Piptocalyx, and Glossocalyx.The mesophyll is loosely organized with relatively large intercellular spaces except in Amborella, Trimenia, and Piptocalyx.Idioblasts, other than ethereal oil cells, are of rare occurrence in the mesophyll, e.g.stone cells in Wilkiea macooraia (Baill.)Perkins (Brass 2265).It is significant in this connection, however, that large "mucilage cells" are formed in both the leaves and stems of Trimenia and Piptocalyx, a structural feature that has been utilized previously as a reliable criterion in differentiating the Lauraceae from the Monimiaceae.The variating venation pattern of the lamina resembles that of several other dicotyledonous families, and the degree of jacketing of the veins and veinlets by thick-walled cells varies greatly even within tribes and genera.The vascularization patterns of the petiole and costa will be considered in connection with the nodal anatomy of the family.The occurence, form and distribution of crystals of calcium oxalate vary markedly, not only within tribes and genera, but also within species, at least in certain cases.When present, the crystals are relatively small and commonly are of diversified form, acicular, elongated prismatic,