Anther culture for haploid induction of buckwheat was studied over a period of five years. Approximately 24,000 anthers were isolated and cultured on different culture media. The regeneration capacity was generally very low. Data are presented for experiments that included 7278 anthers on which 99 calluses were formed and 20 buds regenerations were noted. Regeneration occurred most readily on gellan-gum solidified media, with 90g1-1 maltose, 2.5 mgl -I BA, 0.5 mg1-1 IAA, and preferably in darkness. Haploid cells, as established by chromosome counts, were observed in eight regenerants. Several abnormalities of pollen development in vitro were detected. Starch presence in pollen as a possible sign of androgenic capacity was studied. Microspores in uninucleate and early binucleate stages contained only proplastids, while in adult pollen grains a number of amyloplasts were present.

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Axillary buds of the dioecious plant Rumex acetosella L. were isolated and cultured in vitro. The callus tissue which developed at the basal parts of the explants displayed a high capacity for shoot formation. This morphogenetic pattern was predominant on Murashige and Skoog (MS) medium supplemented with 2% sucrose, 2.2 mg 1-~ benzylaminopurine and 0.17 mg 1 -a indole-3-acetic acid. Somatic embryogenesis was induced when the osmolality of the medium was increased by adding 6% sucrose instead of 2%, or hexitols in addition to 2% sucrose. Most of the embryogenic calli were formed on the basal parts of leaf laminae and bracts. Development and maturation was strongly promoted by transferring the tissue to a solid or liquid medium lacking benzylaminopurine and indole-3-acetic acid and supplemented with 10mgl -~ gibberellic acid. The embryos germinated and developed into normal rosette plants when transferred to vermiculite moistened with hormone-free, half-strength MS salt solution. The histology of successive embryogenic stages is presented.