Meristem characteristics of normal, afila (af), acacia (tl), reduced stipule (st), and combinations of these leaf phenotypes were investigated in pea (Pisum sativum L.). The multiple tendrils of the afila leaf are formed from numerous secondary branches on the leaflet primordia. Adaxial and marginal meristems are absent in afila leaflets. The tendril-like morphology of the terminal and secondary branches of the afila leaflets is derived from a radial marginal meristem, which is characteristic of normal tendril development. The small terminal leaflet lamina on tendrils of the acacia leaf is produced by adaxial and marginal meristems which become apparent in the distal portion of the tendril late in leaf ontogeny. The reduced stipules of the reduced stipule leaf result from early loss of abaxial and adaxial stipule marginal meristems. Combinations of the af, tl, and st genes apparently have no modifying influences on their mutual expression with one exception; the aftlst mature reduced stipule is significantly wider than stipules in st, afst, and tlst phenotypes. The greater final width of triple recessive stipules is attributed to the persistence of the adaxial stipular marginal meristem in this phenotype.

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Tepfer, S. S., R. I. Greyson, W. R. Craig, and J. L. Hindman. (U. Oregon, Eugene.) In vitro culture of floral buds of Aquilegia. Amer. Jour. Bot. 50(10): 1035–1045. Illus. 1963.—Floral buds at various stages of development, from early stages before sepal initiation to late stages with young carpel primordia present, were grown in culture on various agar media. A basic medium containing White's minerals, Nitsch's trace elements, coconut milk, sucrose, and assorted water‐soluble vitamins was developed for growth of the buds. The addition of indoleacetic acid, gibberellic acid, and kinetin to the basic medium extended the developmental limits of buds at nearly all stages and decidedly improved the continued development of carpels. On this medium buds produce all of their organ primordia, growing from early stages to about the size of flowers at anthesis, but will not develop unless the sepals are removed. This inhibiting effect of sepals is not understood at this time. Stamen development is consistently poor beyond the point of differentiation of anther and filament, even with the addition of hormones. The development of buds in culture is illustrated and compared with development in intact plants. With further improvement of the medium, it is hoped that these buds may be used for experiments testing theories of floral morphogenesis.