Physiologische Studien an Hymenophyllaceen

SummaryPlants have followed two principal (and contrasting) strategies of adaptation to the irregular supply of water on land, which are closely bound up with scale. Vascular plants evolved internal transport from the soil to the leafy canopy (but their 'homoihydry' is far from absolute, and some are desiccation tolerant (DT)). Bryophytes depended on desiccation tolerance, suspending metabolism when water was not available; their cells are generally either fully turgid or desiccated. Desiccation tolerance requires preservation intact through drying-re-wetting cycles of essential cell components and their functional relationships, and controlled cessation and restarting of metabolism. In many bryophytes and some vascular plants tolerance is essentially constitutive. In other vascular plants (particularly poikilochlorophyllous species) and some bryophytes tolerance is induced by water stress. Desiccation tolerance is adaptively optimal on hard substrates impenetrable to roots, and on poor dry soils in seasonally dry climates. DT vascular plants are commonest in warm semiarid climates; DT mosses and lichens occur from tropical to polar regions. DT plants vary widely in their inertia to changing water content. Some mosses and lichens dry out and recover within an hour or less; vascular species typically respond on a time scale of one to a few days.© New Phytologist (2002) 156 :

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“…The external hydraulic resistance varies with water content, but will generally be low. Redrawn from Proctor (1982, 1990).…”

Section: The Soil–plant–atmosphere Continuummentioning

confidence: 99%

“…Hymenophyllum spp.) behave much like bryophytes of similar sheltered humid habitats; they lose and absorb water readily over the whole leaf surface and water conduction by the vascular system is limited (Härtel, 1940); they recover remarkably quickly from periods of a few days dry (Fig. 6).…”

Section: Time‐scale Considerations and Ecological Adaptationmentioning

confidence: 99%

Poikilohydry and homoihydry: antithesis or spectrum of possibilities?

2002

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“…The absence of differentiated blade tissues including epidermis and a well-developed cuticle causes a dependence on environmental moisture, because no barrier exists to prevent unregulated loss of water (e.g. Haertel, 1940). Filmy ferns are therefore strongly hygro- , terrestrial species with short, stout stem, robust roots and erect approximate fronds, habitus.…”

Section: Trichomanes Ecologymentioning

confidence: 99%

Ecological diversity and adaptive tendencies in the tropical fern Trichomanes L. (Hymenophyllaceae) with special reference to climbing and epiphytic habits

Dubuisson

Hennequin

Schneider

2003

Botanical Journal of the Linnean Society

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Among the basal fern families, the Hymenophyllaceae, with more than 600 species, display a high diversity in terms of their morphology and the habitats that they occupy. We have chosen to focus on Trichomanes L., a clearly defined genus for which a phylogeny is presently being developed, to investigate the appearance of the climbing and epiphytic habits, as well as the related supposed adaptive characters. In this study we present the first review of the different ecological types within the genus: terrestrial, climbing (divided into hemi‐epiphytic forms and true lianas), and epiphytic types. The study of several features concerning stem morphology and leaf size allows a proposal on relationships between ecology and plant morphology. Terrestrial species display a thick monocaulous rhizome with robust roots and short internodes. Climbing species are characterized by a branched, thick, creeping rhizome with long internodes. Epiphytic species also exhibit long, creeping and branching stems with long internodes but the rhizome is fine to filiform. Under these circumstances, there is a reduction of root system and frond size leading to dwarfism in numerous instances. This may be related to an extreme hygrophilous epiphytic strategy. Finally, hypotheses on the evolution of these habits and hence on the evolutionary relationships between ecology and characters are presented and discussed. © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society, 2003, 142, 41–63.

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“…Although the physiological organization of the filmy ferns has yet to be investigated, some experiments in which micropotometers have been used have shown that in Hymenophyllum demissum (an epiphyte of New Zealand) and Trichomanes radicans the vascular system in the petiole is a poor conductor of water, the amount passing through it being incapable of maintaining the turgidity of the frond at 95 % relative humidity (Hartel, 1940), The vascular tissue in the petiole of T. proliferum is so meagre that here, too, little if any water may pass to the lamina through it. It is noteworthy that on Gunong Poe, and probably elsewhere, this species is confined to the lower metre of the mountain forest where, according to the results of Richards (1936), obtained on a neighbouring mountain and at about the same altitude, the saturation deficit changes least throughout the day.…”

Section: The Frondmentioning

confidence: 99%

THE MORPHOLOGY AND CYTOLOGY OF SPOROGENESIS OF TRICHOMANES PROLIFERUM BL.

Bell

1960

New Phytologist

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Summary The morphology of Trichomanes proliferum is described and the anatomy of the petiole and rhizome is discussed in relation to the habitat of the plant and its growth. It is suggested that after the initial phases each frond may be regarded as a more or less independent colony of cells, the complexity ultimately attained by the frond depending upon the supply of primary metabolites reaching it directly from without. It is reported that in the plant collected from Gunong Poe the chromosomes failed to pair at meiosis and 108 univalents were present. A means is suggested by which polyploidy could have arisen frequently in the Hymenophyllaceae.

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Physiologische Studien an Hymenophyllaceen

Cited by 24 publications

References 18 publications

Poikilohydry and homoihydry: antithesis or spectrum of possibilities?

Poikilohydry and homoihydry: antithesis or spectrum of possibilities?

Ecological diversity and adaptive tendencies in the tropical fern Trichomanes L. (Hymenophyllaceae) with special reference to climbing and epiphytic habits

THE MORPHOLOGY AND CYTOLOGY OF SPOROGENESIS OF TRICHOMANES PROLIFERUM BL.

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