THE STOMA.TAL RELATIONSHIPS, LEVELOPl^IENT, AND MATURE STRUCTURE OE SOME AMARYLLIDACEOUS LEAVES._______ An in v e s t ig a t io n has been made o f: i) Variations in the number and form of the stomata, papillae, and ordinary epidermal cells over the individual leaf. ii) Growth of the leaf with special reference to meristematic activity, and the vascular system. iii) Comparative anatomy of Amaryllidaceous leaves with special reference to the inverted bundle system. Variations in the water supply to the successive intercalary portions of the leaf cause variations in the degree of expansion of the epidermal cells. This modifies the stomatal freq.uencies (numbers per unit area) as otherwise determined by the index value (proportion of epidermal units converted into stomata). The typical frequency gradients are: i. Increasing gradient from base to­ wards the apex of the leaf, with a secondary decrease at the apex. ii. Increasing gradient from the mid-rib to the margin for broad leaves, and decreasing for narrow leaves. Stomatal indices are more constant than frequencies, but give similar gradients. The basal growth of the leaf-limb is due to: i. Meristematic activity and auxesis of the peripheral tissues forming the epidermis and assimilating tissues. ii. Auxesis only of the central ground-tissue. The extent of mature leaf-limb increases during growth but its water supply is limited by the amount that can be conducted through the extending zone. This supply improves due to the lignification of the immature tracheids present in the dormant l e a f . In only six genera of the Amaryllidaceae are concentric leaves found excluding the Conostylideae. These leaves have adaxial inverted bundles which were found to differ in their mode of connection with the stem system. They may curve round into the sheathing portion of the leaf- base, passing directly to the stem system as in lanthe, or they may be independent, ending in groups of storage tracheids in the upper part of the leaf-base, as in Narcissus roeticus. and Zeohvranthes Candida. It is difficult to harmonise the results from the two latter with the Phyllode theory. ^ THE STOMATAL RELATIONSHIPS, DEVELOPMENT AND MATURE STRUCTURE OF SOME AMARYLLIDACEOUS LEAVES. by L i l l i a n Mary W icks. CONTENTS. General Introduction. Part I. The variations in number and form of the stomata, papillae, and ordinary epidermal eells over the individual leaf as found in the Amaryllidaceae. Broad Leaves. i. Hae man thus eocoineus,L. ii. Haemanthus rotundifolius, Gawl. iii. Haemanthus albiflos, Jacq. ( a note) iv. Brunsvigia gigantea, Heist. V. Hymenoeallis festalis, ( «Hymenooallis calathina, Nichols, x Elisena longipetala. H erb.) Narrow Le ave s . i. Galanthus nivalis, L. ii. Ammo char is falcata, (L^H^rit) Herb. iii. Narcissus poeticus, L .- Summary. Description of figures. F ig u r e s . Part II. The anàtomy of the Dormant Leaf, and of the leaf at various stages of Growth with special reference to meristematic activity and the vascular system. Description for Narcissus poeticus, L. and comparison with N.Elvira ( s N. poeticus,L. var. ornatus, Haw. X N. tazetta, L.) ProQuest Number: 10097160 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. uest. ProQuest 10097160 Published by ProQuest LLC(2016). Copyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code. Microform Edition © ProQuest LLC. ProQuest LLC 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106-1346 Introduction Section. 1. Prior to the resting stage. ( N. hulbocodium,L. var. citrinus,BakO 2 . Resting stage. 3 . Half-grown leaf. 4 . Mature leaf. 5 . Comparison of the growth of leaves of Narcissus with those of Galanthus nivalis, L. and Zephyranthes Candida, Herb.. ti 6 . Anatomy and growth of the scale leaf and comparison with that of Haemanthus albiflos, Jacq. Summary. Description of figures. F ig u r e s . P a r t. I I I . Comparative anatomy of Amaryllidaceous leaves with special reference to the inverted bundle system. Section. 1. Anatomy of the bi-facial leaf. 44 2. Extent of the concentric leaf type in the family and its structure. it 3. The origin and significance of the inverted bundle system. (a) lanthe alba, (linn, fil.) Salisb. lanthe aquatica. (Linn.fil.) W illia m s. (b) Agave americana, L. (c) Narcissus poeticus, L. (d) Zephyranthes Candida, Herb. Discussion on the Phyllode Theory and the concentric leaf. Summary. Description of Plates and figures. Plates and figures. Note on Nomenclature. Literature cited. GENERAL INTRODUCT ION. I. The Interesting results obtained by Salisbury when considering the variations in the stomatal distribution (frequencies) over the Individual leaf suggested the desir­ ability of extending such work to other leaf types. It was also desired to study more fully the interaction of stomatal index (the proportion of epidermal units converted into stomata) and the expansion factor (of the ordinary epidermal cells) in determining the flrequency variations. An attempt has been made to correlate these variations with the variations in water supply during growth. Where papillae are present their mature structure has been described and their distribution considered in the same way as for the stomata, that is, the variation in frequency and index values (the proportion of epidermal units converted into papillae ) have been considered. II. It has been known for a long time (Steihheil 1837)that many leaves grow for a considerable period due to the activity of a basal zone and that the apex of the leaf-limb is the oldest portion. It was desired to find the extent and period of activity of this meristem and to define the part played by auxesis. If the apex of the leaf is mature and transpiring, the problem arises as to how the water-supply to it is main­ tained through the growing zone, that is, how are the vascular tissues in that zone able to undergo great extension and at the same time conduct an adaquate supply of water to the mature leaf-lim b, which is continously increasing in extent and demand on the water supply. III. The general survey of Amaryllidaceous leaves was under­ taken to find the relationship of the assimilating tissue to the vascular system, and to find how frequent is the occurrence of the concentric type of leaf within the family. In examining the bases of some leaves with concentric leaf-lim bs inverted bundles were not found in the leaf-base. It soon became obvious that the relationship of this system to the normally orientated one of the stem varied, so a critical in v e s t ig a t io n was made o f a s many d if f e r e n t ty p e s as cou ld be fo u n d . FART I. THE VARIATIONS IN NUMBER AND FORM OF THE STOMATA, PAPILLAE, AND ORDINARY EPIDERMAL CELLS OVER THE INDIVIDUAL LEAF - AS FOUND IN THE AIvIARYLLIDACEAE. A considerable amount of work has been done on the comparison of the structure of the lower and upper leaves of the individual plant. (Zalenski 1904, Yapp 1912, and others). The variations in structure of the leaves belonging to different tiers of a woodland flora have also been invest­ igated in detail (Salisbury 1927). But at present comparat­ ively little detailed work has been done on the variations over the individual leaf. Salisbury (Phil. Trans. Roy. Soc. B. vol. 216,1927 p. 20 - 2 5 ) examined the epidermis of some elongated monocotyledonous leaves and found that the stomatal frequency (the number of stomata per unit area of leaf surface) increases from the base to the apex of the leaf, and from the mid-rib to the margin. He found that these gradients are of ‘‘widespread occurrence,** but are sometimes modified. Thus the leaves of Garex sylvatica show a rapid increase in the frequency values for a short distance from the base of the leaf, followed by a gradual fall towards the apex. Salisbury ( ibid p . 5 0 ) considers the proportion of epidermal units converted into stomata. The numerical relationship he terms the Stomatal Index, for which he gives the formula: I - S/E.t S x 100, where I = the stomatal index, S - the number of stomata per unit area, and E = the number of epidermal cells for the same unit area. Salisbury found that the index values for a given species are more constant than the frequencies which indicates that the variations in the frequency values aie due rather to differences in the degree of expansion of the epidermal cells. Salisbury worked mainly with comparatively small linear leaves. This part of the present investigation is an attempt to extend this work taking other leaf types. For this the large leaves of some Amaryllidaceous species are particularly suitable. METHOD. Counts were made of the epidermal constituents, (stomata, papillae if present, and ordinary epidermal cells) at frequent intervals in various parts of the leaf, chiefly along the margins and the median line of the leaf. Gell counts were made with an E. Leitz Wetzlar projection apparatus by means of which the piece of epidermis under observation was re­ flected on a sheet of paper and each cell indicated by mark­ ing the position of its nucleus. At the same time a certain portion of the field was drawn accurately so that the variation in the degree of expansion of the cells could be found.