THE COMPARATIVE MORPHOLOGY OF THE CANELLACEAE. II. ANATOMY OF THE YOUNG STEM AND NODE

The anatomy of the young stem and node was investigated in 12 species representing all 6 genera of the Canellaceae. The salient anatomical features of this family are as follows: (1) the primary vascular system is pseudo-siphonostelic; (2) druse-type calcium oxalate crystals and ethereal oil cells are characteristic of the parenchymatous tissues; (3) all members of the family exhibit trilacunar nodes; (4) the periderm is superficial in origin with characteristic U-shaped thickened cells; and (5) the sieve-tube members are of a primitive type with obliquely oriented end walls and many unspecialized sieve areas. On the basis of this anatomical investigation, the conclusion that the Canellaceae has a general ranalean affinity is strengthened. IN THE first paper of this series (Wilson, 1960) it was concluded, on the basis of wood anatomy, that the affinities of the Canellaceae appear to be with the woody Ranales. However, at that time it was also noted that it is extremely dangerous to base such a conclusion on wood anatomy alone. Accordingly, it is desirable that this tentative conclusion be validated by evidence from other organs of the plant. A review of the systematic literature of the Canellaceae is presented elsewhere (Wilson, 1960) and will not be repeated here. In this present paper, details concerning the anatomy of the young stem and node are presented. MATERIALS AND METHODS-Material of all genera of the Canellaceae has been examined. Table 1 lists the genera and species studied with their source and collector. Preserved specimens weire dehydrated, infiltrated and embedded in paraffin according to the usual technique. Wax infiltration was facilitated (and subsequent sectioning improved) by the use of a vacuum oven with a vacuum of 600 mm of mercury (Wittlake, 1942). Sectioning was done with a rotary microtome; staining, with one of the following combinations: (1) safranin 0-nmethyl violet 2B-fast green FCF; (2) safranin 0-aniline blue; (3) Bismnarck brown-methyl greeii-lacmoid. The last combination was particularly suitable for the 1 Received for publication July 17, 1964. The publication of the excess pages was aided by the Graduate School, University of Cincinnati. The author wishes to thank Dr. J. E. Canright for reading the manuscript and offering many helpful suggestions and the curators of the following institutions for the loan and/or gift of specimens of the Canellaceae: Missouri Botanical Garden, Philadelphia Academy of Science, New York Botanical Garden, Rio de Janeiro Botanical Garden, Chicago Natural History Museum, U. S. National Museum Herbarium (Smithsonian Institution), Paris Museum of Natural History, the East African Herbarium, and the Department of Agriculture, Union of South Africa (Pretoria). Without their assistance this study would not have been possible. study of phloem as the lacmoid is apparently specific for callus material (Esau, 1938). The safranin 0-aniline blue combination proved useful in studying sections with little lignification of the vascular elements. Satisfactory handling of dried or herbarium material presented several unique problems. In order for this type of material to be of value, it must be restored to a semblance of its original condition. The technique inivolving warm ammornium hydroxide, as described by Venning (1954, p. 44), was first used. However, this was not adequate. A better technique was eventually found using weak sodium hydroxide (2.5-5%) followed by corncentrated chloral hydrate (cf. Carlquist, 1957; Foster and Arnott, 1960). Since this method was modified somewhat from the method suggested, it is given here in some detail. Small portions of dried stems were placed in a 1% detergent solution and left on top of an embedding oven overnight. Then the specimens were tranisferred to a 2.5% solution of sodium hydroxide and left for about a week. After washing briefly, the specimens were treated for 2-4 weeks in a concentrated solution of chloral hydrate. (The exact time of treament with chloral hydrate was dependent on the nature of the material. Once clearing had started, the optimum degree of restoration was apparently past, and the material became quite soft.) The restored specimenis were next treated with either CRAF III (Sass, 1951) or Lavdowsky's fluid (Gray, 1958). This last step was found to be essential for good staining. After washing to remove the fixing fluid, the material was dehydrated, infiltrated and enmbedded in wax. Again, the use of a vacuum oven to aid infiltration greatly facilitated subsequent sectioning. The combinations of stains listed above were used. This method of restoring, far from being universally successful, gave the most reliable results. Unequal expansion was reduced to a mininmum. In spite of the moderate success