摘要:

Abstract1)2‐Thiouracil (2‐TU) applied during low temperature treatment, inhibited flower formation in excised stem discs of Wedgwood iris. The inhibition was overcome by gibberellic acid (GA) and orotic acid but not by uracil or thymidine.2)The first signs both of an inhibitive effect on flower initiation by 2‐TU and of GA promotion occurred at the beginning of the reproductive stage. Increase or decrease of the rate of development of the flower primordium could be established only two weeks later, during differentiation of stamens or tepals.3)The peak in respiration rate occurring in the bud at the beginning of the reproductive stage was entirely repressed by 2‐TU and not restored on a medium containing 2‐TU and GA.4)It is concluded that a specific RNA takes part in the earlier stages of flower formation in Wedgwood iris.5)The role of gibberellih‐like substances in flower formation of the Wedgwood iris is discussed in the light of possible interaction with nucleic acid

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1966.tb00227.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

AbstractAfter an enumeration of the most characteristic features of theOrchidales, the affinities between this order and other monocotyledonous groups are discussed. TheOrchidalesmust be placed in the system immediately after theCommelinales, chiefly on account of their androecial morphology. For reasons explained in the present paper theOrchidalesare subdivided into three families, viz. theApostasiaceae, CypripediaceaeandOrchidaceae. The principal differences between these families are shown in the form of tables.In theOrchidaceaetwo subfamilies are recognised and amply circumscribed, viz., theOrchidoideaeand theEpidendroideae, the latter again being subdivided into the two contribesNeottianthaeandEpidendranthae.The androecial morphology is discussed in detail in connection with atavistically developed stamens, with the presence of staminodes (or supernumerary stamens) and with the floral morphology of certain taxa. The auricles are not regarded as staminodes because they persist in flowers with supernumerary (atavistically re‐appeared) stamens and also because they lack vascular bundles. The gynostemial wings in some Australian genera(Diuris, Prasophyllum, and other ones) are considered to be of androecial derivation The less conspicuously winged but vascularised margins of the gynostemium of manyEpidendroideaelikewise represent androecial elements incorporated in the column.The suggestion, made by E. Nelson, that the lip is the phylogenetic derivative (the homologue) of the ‘missing’ stamens A2, a3and A3(which implies that the median petal has disappeared), is rejected, primarily because Nelson's arguments are based on the morphology of the labellum in the highly specialised genusOphrys. The floral morphology ofNeuwiediaand of some species ofHerminium, on the contrary, is indicative of the petaloid nature of the lip which, accordingly, represents the median petal. The vascular anatomy of the orchid flower does not provide arguments in favour of the suggestion made by Lindley (later taken up by Darwin) that the ‘missing’ stamens A2and A3are incorporated in the gynostemium.The orchidalean ovary appears to be compounded of six parts, viz. three broad hyposepalous zones alternating with as many hypopetalous elements bearing the (double) laminal placentae on their inner face. This is considered to be a convergence towards the condition prevailing inRhoeadales (Brassicales) (genusEschscholziaetc.).In theOrchidoideaethe stigma is locally differentiated into viscid discs which are situated distally of the lateral stigmatic lobes, and the median stigmatic lobe is functional in several genera, but in theEpidendroideaethe median stigmatic lobe is apically transformed into a mucilaginous substance or a viscid disc, or it is completely replaced by a viscidium. InStereosandrathe viscidial element is a derivative of t

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1966.tb00228.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

Book reviewed in this article:A. G. VOORHOEVE, Liberian High Forest Trees.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1966.tb00229.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY