Chromosome Pairing in <i>Yucca flaccida</i>

Chromosomes and Compatibility in the Aloinae

“…Taylor (1925) has made careful comparisons of the chromosome morphology in some species of Aloe, Gasferia, and Hauiorthla, and has found as the haploid complement in all, four long and three short chromosomes. A similar complement of five long and twentyfive short pairs of chromosomes has been described in the Central American genera Yucca and Agave (O'Mara, 1931;McKelvey and Sax, 1932). The odd one has its constriction somewhat further removed from the end and bears a " satellite" at the distal end.…”

“…

In the course of some cytological investigations data were obtained on chromosome number and form in the Aloinae which may be of interest to the systematist.

Taylor (1925) has made careful comparisons of the chromosome morphology in some species of Aloe, Gasferia, and Hauiorthla, and has found as the haploid complement in all, four long and three short chromosomes. A similar complement of five long and twentyfive short pairs of chromosomes has been described in the Central American genera Yucca and Agave (O'Mara, 1931;McKelvey and Sax, 1932).In the present investigation descriptions are based only on figures from the first pollen grain division. The odd one has its constriction somewhat further removed from the end and bears a " satellite" at the distal end.

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Meiosis in <i>Lilium</i>

“…This theory was criticised by O'Mara (1931) on the ground that in Yucca he found more pairing of small chromosomes than would be expected on Darling ton's theory. The work of Darlington and Dark (1932) removed the basis of this attack.…”

Cytosystematik, bimodale Chromosomens�tze und permanente Anorthoploidie beiOnosma (Boraginaceae)

“…Zwar wurde aueh ftir stabile kleine Chromosomen verschiedentlich der Ausdruck B-Chromosom verwendet, doch ist er, fibereinstimmend mit der iiberwiegenden Mehrzahl der Autoren, die ihn fiir innerhalb yon Arten, Populationen und oft auch Individuen instabile, meist heterochromatische und durch verschiedene weitere Eigenschaften ausgezeichnete Chromosomen verwenden, hier nicht angebracht. Der Begriff Mikrochromosom, der vor allem fiir die kleinen Chromosomen in den bimodalen Ss yon Reptilien und VSgeln herangezogen wird, ist auch auf die kleinen Chromosomen yon Agavaceen angewendet worden (O'MARA, 1932 ;SWAnSOn, 1960 : 403) ;allerdings wird ,,Mikrochromosom" auch ,,Fragment" und ,,B-Chromosom" gleichgesetzt (z. B. DARLINGTON, 1965), so dab der Terminus nicht eindeutig ist; aul3erdem ist er als Abkiirzung schlecht zu gebrauchen, da M und m schon g~ngig fiir metazentrische oder mittelgrol3e:Chromosomen verwendet werden.…”