Planta (1989) 177:6(~73 Planta 9 Springer-Verlag 1989 A kinematic analysis of tepal growth in Lilium longiflorum Kevin S. Gould * and Elizabeth M. Lord** Department of Botany and Plant Sciences, University of California, Riverside, CA 92521, USA Abstract. Time-lapse marking experiments indicate that the growth of tepals in Lilium longiflorum Thunb. from 3.7 mm to maturity is triphasic. Phase I (tepal lengths 3.7-10 ram) is characterized by spatial and temporal variation in growth rate and, in the epidermis, a random distribution of mitoses with an acropetal increase in cell area. During phase II (10-90 mm) cell elongation and (later) cell division is restricted largely to basal re- gions. Cell division ceases when tepals are less than one-third of their mature length of 155 mm. Phase III (90-155 ram) is characterized by the gradual transition from basal to apical growth, and a modi- fication of epidermal cell shape. A sharp peak in growth at the extreme tip of the tepal coincides with anthesis. Key words: Cell division - Cell size - Growth anal- ysis - Lilium (tepal growth) - Tepal growth Introduction There is a paucity of quantitative information on the growth and development of floral organs. This is despite Greyson's (1972) proposition that de- scriptions of changes in the relative contributions of cell size and cell number to growth patterns are powerful tools for examining phylogenetic trends. Previous workers have described the onto- geny and histogenesis of the perianth (Satina 1944; Boke I948; Tepfer 1953; Tucker 1959; Kaplan 1968; Dermen and Stewart 1973; Nishino 1976) and-or the fusion events leading to the formation * Present address: Department of Botany, University of Auck- land, Private Bag, Auckland, New Zealand ** To whom correspondence should be addressed Abbreviations: LRGR = local relative growth rate; RER = rela- tive elemental rate of growth of a corolla tube (Daniel and Sattler 1978; Nishino 1978, 1982, 1983a, b; Dubuc-Lebreux and Sattler 1984). Boke (1948) determined from staining inten- sities of cells in transverse and longitudinal section that, for Vinca rosea, both sepal and petal primor- dia exhibit a short initial period of apical and mar- ginal growth followed by intercalary growth near the base. Daniel and Sattler (1978) provided good quantitative data on the spatial distribution of mi- toses from sections of four corolla tubes of Solan- um dulcamara following colchicine treatment. Conclusions on the growth of an organ based on sections alone presuppose (i) a steady-state dis- tribution of growth centers, and (ii) a close rela- tionship between meristematic activity and actual enlargement of the organ. Marking experiments have shown that in lily anthers, the regions of growth are constantly shifting, so that a longitudi- nal section through any one developmental stage would overemphasize the importance of growth of a particular region (Gould and Lord 1988). In the absence of kinematic data on the distribution of growth, the same criticism might well hold true for the perianth. If the growth of the perianth is indeed a nonsteady system, then the colchicine treatment used by Daniel and Sattler (1978) could have masked local differences in cell-division activ- ity, producing instead a cumulative picture of all the dividing regions over the exposure period. Moreover, there is evidence that organ enlarge- ment and the pattern of cell division are not tightly correlated. Both shoots and roots can grow nor- mally for a period after cell division has been com- pletely inhibited by irradiation with gamma rays (Foard and Haber 1961 ; Haber 1962; Foard 1971), or following colchicine treatment (Foard et al. 1965). We aim to provide a kinematic description of perianth growth, by providing quantitative data