摘要:

FOUNTAIN, D. W., HOLDSWORTH, J. M.&OUTRED, H. A., 1989.The dispersal unit ofDacrycarpus dacrydioides(A. Rich.) de Laubenfels (Podocarpaceae) and the significance of the fleshy receptacle.Dacrycarpus dacrydioides(formerlyPodocarpus dacrydioides) is an arborescent gymnosperm endemic to New Zealand. The high water content (43%) and sensitivity of viability towards desiccation, suggest the seeds are of the ‘recalcitrant’ type. The ‘fruits' comprising a seed borne on a fleshy receptacle arc shed in large numbers. The development of the seed precedes the full development of succulence in the receptacle and at maturity the seed has a high relative water content (RWC) relative to the receptacle. Within the maturing reproductive unit, the receptacle buffers the seed against the effects of water stress. After shedding, seeds are rapidly desiccated in moving air, and viability is impaired below approximately 80“’ RWC and abolished at 34”, seed RWC. The presence of the receptacle during drying confers resistance to desiccation‐associated damage. Five phases of desiccation sensitivity are distinguished in recognition of the protective role of the receptacle. It is suggested that the advantages associated with prolonging seed viability may have contributed to the evolutionary development of succulence in the reproductive unit. This might be considered as a selection pressure in a manner similar to the proposal that such fleshy structures are associated with seed dispe

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1989.tb00399.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

TOMLINSON, P. B., TAKASO, T.&RATTENBURY, J. A., 1989.Cone and ovule ontogeny inPhyllocladus(Podocarpaceae).Cones are borne directly on phylloclades, usually in the position of basal segments or as segment appendages. Each cone consists of a series of spirally arranged bracts, of which the middle bracts each subtend a single, sessile ovule. There is no ovuliferous scale. Ovules arise as ovoid outgrowths; integument development involves periclinal divisions of hypodermal cells with the integument becoming bilobed and extended laterally. The mature ovule is flask‐shaped. The integument includes an extensive middle region bounded by an inner and outer epidermis; the outer hypodermis is differentiated as two contrasted cell layers. An aril differentiates late by periclinal divisions of the outer hypodermal cells at the base of the ovule. The three outermost layers of the integument become differentiated in the mature seed as an epidermis, with thick, cutinized outer tangential walls, an outer hypodermal tanniniferous layer and a sclerotic inner layer. Each ovule is vascularized by two strands that diverge from the axial bundles delimiting the gap left by the departing bract trac

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1989.tb00400.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

TOMLINSON, P. B., TAKASO, T.&RATTENBURY, J. A., 1989.Developmental shoot morphology inPhyllocladus(Podocarpaceae).Shoot architecture in the adult phase ofPhyllocladusis established by a succession of units of extension that develop a system of permanent axes supporting photosynthetic units (phylloclades) each of which represents a branch complex with three branch orders. Seedlings have needle foliage leaves comparable to those of other conifers, but in adult plants all leaves are ephemeral, non‐photosynthetic scales that for the most part subtend no axillary buds. Once rhythmic growth (usually seasonal) is established in the adult phase, each increment produces a whorl of phylloclades so that a regular tiered arrangement develops, with the tiers progressively reduced on outer units. In the resting terminal bud of permanent axes only scale primordia are present; with bud burst and beginning of extension of the unit the phylloclades are produced by syllepsis and complete the initiation and expansion of all axis orders in the short flushing cycle. Segments retain strict distichy throughout, but in a dorsiventral and not a lateral plane. Phylloclades may be either determinate, when the apex of the first‐order axis develops as a terminal flattened segment, or indeterminate, when the apex retains radial symmetry and forms a resting bud that can continue axis extension as a permanent shoot in subsequent years. A phylloclade consequently only produces flattened lateral segments in its season of initiation. Reiteration from reserve buds is not possible, because none are produced in the adult phase, but is possible from detached meristems formed in the axils of needle leaves on juvenile shoots. Reiteration in the adult phase is thus possible only by axis dedifferentiation, that is, change from plagiotropy to orthoptropy. The distinctive massive vascular connection of the phylloclade is made possible by syllepsis. In this way the normal structural constraints of elaborate appendage development in conifers is fully overc

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1989.tb00401.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

NELSON, E. C, 1989.DionaeaSolander ex J. Ellis (Droseraceae): Notes on the nomenclature and typification of Venus's Fly‐trap.The nomenclatural history of Venus's flytrap,Dionaea muscipula(Droseraceae) from North America (Carolinas), is discussed. The binomial was first published in a London newspaper at the beginning of September 1768 by John Ellis who credited the generic name to Daniel Solander. A lectotype is designate

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1989.tb00402.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

PHILLIPSON, P. B., 1989.Taxonomy ofMonopsis(Lobeliaceae):At. scabraandM. unidentata.The long‐standing taxonomic instability of theMonopsis scabragroup of species is discussed. The group is shown to comprise two distinct species:M. scabraandM. unidentata.The typification of the two species and their numerous synonyms is discussed, and lectotypes are selected where necessary. WithinM. unidentatathree subspecies are recognized, one new subspecies is described and one new subspecific combination is made. Diagnostic descriptions of the taxa are given, and their relationships with other species of the genus are discussed. Five hundred and sixty‐nine herbarium specimens were examined, representing 375 separate collecti

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1989.tb00403.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

KOZAKIEWICZ, Z., 1988.Ornamentation types of conidia and conidiogenous structures in fasciculatePenicilliumspecies using scanning electron microscopy.As part of a multidisciplinary approach to the taxonomy of the fasciculatePenicilliumspecies, the conidial ornamentation of 320 strains was examined in order to determine the types and range of ornamentation and assess the stability of this feature as a taxonomic character.Five conidial ornamentation classes were identified: echinulate, tuberculate, reticulate, microtuberculate and microverrucate. The technique of cryoscanning was used for examining the penicillus, and assessing such characters as roughening, shape and orientation of the branches. The method provides a fast means of examining freshly frozen material in the absence of artefacts associated with air‐drying, freezing and critical‐point drying techniques.Studies on large numbers of conidia from the same isolate and from isolates referred to the same species showed the scanning electron microscopy results to be reproducible and provide an objective and accurate method for comparing micromorphological features. The ornamentation types can be of particular value in species identificat

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1989.tb00404.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Fundamentals of Palaeobotany by S. V. Meyen.Kew Index for 1987: names of seed‐bearing plants, ferns, and fern allies at the rank of family and below published during 1987 with some omissions from earlier years. Compiled by R. A. Davies and K. M. Lloyd.Collins Photoguide to Wild Flowers of Britain and.Northern Europe, by the late Oleg Polunin; text prepared for publication by John Akeroyd; line drawings by Rosemary Wise.Five Kingdoms, 2nd edition, by Lynn Margulis&Karlene V. Schwartz.Biomechanisms Regulating Growth and Development, edited by George L. Steffens&Theron S. Rumse

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1989.tb00405.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY