The ability of the summer flowering Gladiolus dalenii Van Geel and the winter flowering G. tristis L. to form corms in vitro was investigated. G. dalenii spontaneously formed corms on a shoot induction medium consisting of the basal medium of Murashige & Skoog (1962) with up to 2.0mg1-1 benzyladenine (BA), 3% sucrose and solidified with 2 g l 1 Gelrite ®. The effect of different BA and sucrose concentrations as well as different temperatures on in vitro corm production of G. tristis was further investigated. The best production of shoots per explant was achieved on a medium containing 0.5 to 1.0mg1-1 BA, sucrose concentrations of 6 to 9% and cultured at 15°C. The best corm production was achieved at the same temperature and with the same medium with the exception that BA was omitted from the medium. To test the effect of the osmotic potential on the formation of shoots and corms, sucrose was substituted by mannitol at various concentrations. Sucrose proved to be essential for both shoot and corm production and the use of mannitol had no beneficial effect.

Tissue culture techniques were applied to study the regeneration and growth of bulblets from bulb scale segments of Crinum macowanii Bak. (bush-or march lily) in vitro. Shoots were induced on twin scales taken from the basal plate region of flowering-size bulbs on Murashige and Skoog (MS)-medium containing 0 -2 0 m g l -~ NAA and BA and a modified MS medium (MMS medium) containing 1.25 mg !-~ ancymidoi (A-RestrU), 0.1 mg i-1 NAA and 0.1 mg 1-~ kinetin (ANK). Large bulblets could only be initiated on the latter. Subsequently the bulblets of 5 mm or more in diameter were trimmed and split in half, and secondary plantlets were regenerated on MMS-medium containing ANK or MS-medium without any growth regulators which in turn grew into bulblets suitable for splitting within 12-16 weeks.

Amaryllis belladonna L. plants were multiplied successfully by means of tissue culture techniques.Different plant parts were tested as explant material, but plantlets could only be generated from the twin-scales and immature scapes. These in vitro-formed plantlets were divided into four parts and used for further multiplication. The twin-scale explants had the highest multiplication rate when a medium with 22.2 ~M benzyladenine and 0.54 p.M naphthaleneacetic acid was used. The sucrose concentration played an important role in the initiation of new plantlets, and the best results were obtained when a sucrose concentration of 2-3% was used. Anatomical observations were made during the initiation of the new plantlets.

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