Ricerche citotassonomiche nelle Euphorbiaceae: Euphorbia angulata Jacq. ed E. dulcis L.

Abstract

Cytotaxonomical studies in Euphorbiaceae: Euphorbia angulata Jacq. and E. dulcis L. — E. dulcis and E. angulata can be easily distinguished by the following key:

rhizome long, thicker than the stems, swollen and jointed, usually with swellings like ovoid, curved, obliquely jointed bulbils at the base of the stems; ovary and capsule with green or red, uneven tubercles; glands reddish at the anthesis. E. dulcis.

rhizome long, jointed, with globular swellings at the base of the stems; ovary and capsule green, with minute hemispherical tubercles; glands yellow at the anthesis … … … … E. angulata. Chromosome number of E. angulata observed in root tips and in gynospore mother cells is n=5, 2n=10. All chromosomes of the complement are M (middle length) type; two pairs bear nucleolar constrictions. The E. angulata embryo sac development is monosporic (Polygonum type) and, moreover, the ovule development differs from that of E. dulcis. New cytological and embryological data are reported about E. dulcis (2n=12; 3n=18; 4n=24; see also CESCA, 1961). In this species, the occurrence of nucleolar constrictions is now well ascertained on the shortest chromosomes of the complement. Furthermore triploid and tetraploid plants have, respectively, one or one pair of strongly heterobrachial chromosomes. A complete revision of the karyotype will be attempted as soon as possible. The occurence both of adventitious embryony and of the normal embryo have been observed in the same embryo sac in triploids.