Atmospheric condition controlling the seed germination of an achlorophyllous orchid,Galeola septentrionalis

Nakamura, Shigetake; Uchida, Toshiro; Hamada, Minoru

doi:10.1007/bf02491245

Cited by 23 publications

(15 citation statements)

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“…On the other hand there are indications that seeds of Vanilla planifolia and Galeola septentrionalis (probably similar to those of Galeola galeata and Galeola altissima Fig. 1b) may be endoornithochorous (Nakamura & Hamada, 1978). The seeds of the latter may also be or endozoochorous (Hamada & Nakamura, 1978) .…”

Section: Box 3 Darwin On Fruit and Seed Set In Orchidsmentioning

confidence: 98%

“…Both the large number and the physical characteristics of orchids facilitate extensive coverage of areas around the seed parent and wider dispersion further away. A consequence of such dispersal is colonization of new and existing favourable sites (Nakamura & Hamada, 1978 ;Rasmussen, 1995 ;Murren & Ellison, 1996Tremblay, 1997 ;Carey, 1998 ;Kull, 1998, Light & MacConaill, 1998Neiland & Wilcock, 1998 ; for reviews of evolutionary implications of the nature of orchid seeds see Benzing, 1981Benzing, , 1987.…”

Section: mentioning

confidence: 99%

“…1b) may be endoornithochorous (Nakamura & Hamada, 1978). The seeds of the latter may also be or endozoochorous (Hamada & Nakamura, 1978) . There is also a report that orchid seeds are scattered widely with excrement (Beer, 1863 ;Nakamura & Hamada, 1978).…”

Section: Box 3 Darwin On Fruit and Seed Set In Orchidsmentioning

confidence: 99%

“…Treatments with a variety of solvents and surface sterilants suggest that orchid seeds may be able to withstand digestive tracts at least for a while (see Arditti, 1967Arditti, , 1979Arditti, , 1992Arditti & Ernst, 1984). It is possible that ingestion by birds may even enhance germination of Vanilla planifolia seeds because of chemical changes brought about by ' juices ' in the intestinal canal (Bouriquet, 1943 ;Stoll, 1954 ;Nakamura & Hamada, 1978). Chemical attack by digestive fluids could facilitate germination by rendering the testa more permeable to water.…”

Section: Box 3 Darwin On Fruit and Seed Set In Orchidsmentioning

confidence: 99%

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Tansley Review No. 110.

2000

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Orchid seeds are very small, extremely light and produced in great numbers. Most range in length from c. 0.05 to 6.0 mm, with the difference between the longest and shortest known seeds in the family being 120-fold. The ' widest ' seed at 0.9 mm is 90-fold wider than the ' thinnest ' one, which measures 0.01 mm (because orchid seeds are tubular or balloon-like, ' wide ' and ' thin ' actually refer to diameter). Known seed weights extend from 0.31 µg to 24 µg (a 78-fold difference). Recorded numbers of seeds per fruit are as high as 4 000 000 and as low as 20-50 (80 000-200 000-fold difference). Testae are usually transparent, with outer cell walls that may be smooth or reticulated. Ultrasonic treatments enhance germination, which suggests that the testae can be restrictive. Embryos are even smaller : their volume is substantially smaller than that of the testa. As a result, orchid seeds have large internal air spaces that render them balloon-like. They can float in the air for long periods, a property that facilitates long-distance dispersal. The difficult-to-wet outer surfaces of the testa and large internal air spaces enable the seeds to float on water for prolonged periods. This facilitates distribution through tree effluates and\or small run-off rivulets that may follow rains. Due to their size and characteristics, orchid seeds may also be transported in and on land animals and birds (in fur, feathers or hair, mud on feet, and perhaps also following ingestion).

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Section: Box 3 Darwin On Fruit and Seed Set In Orchidsmentioning

confidence: 98%

Section: mentioning

confidence: 99%

Section: Box 3 Darwin On Fruit and Seed Set In Orchidsmentioning

confidence: 99%

Section: Box 3 Darwin On Fruit and Seed Set In Orchidsmentioning

confidence: 99%

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Tansley Review No. 110.

2000

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“…However, it is uncJear how the response to increased atmospheric pressure can be related to the natural habitat of the plant. Nakamura (1476) demonstrated that, whereas Galeola gevminateei asymbiotically at 30 "C, subsequent growth and protocorm de\ elopment only occurs in a narrow temperature range (20-26 °C), which encompasses the maximum soil temperature in its babitat of 22 °C (Nakamura et al, 1975).…”

Section: Asymbiotic Seed Germinationmentioning

confidence: 99%

The biology of myco‐heterotrophic (‘saprophytic’) plants

1994

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SUMMARY More than 400 species of vascular plants, in 87 genera, are acholophyllous and heterotrophic, but not directly parasitic upon autotrophs. They are usually, but incorrectly, described as 'saprophytes’since they are in fact nourished by means of specialized mycorrhizal associations. Although distributed world‐wide, they are most abundant and show the greatest species‐richness in the Neotropics and Palaeotropical regions. Their aerial parts range in size from a few centimetres to extensive liane types up to 40 m long. With few exceptions, their habitats are dense moist forests in which there is a surface accumulation of leaf litter, often in situations which are too shaded for autotrophic growth. Although the achlorophyllous mycorrhizal mode of life has evolved independently many times and in widely disparate taxonomic groups, such plants show strong convergent evolution in particular adaptations to their peculiar mode of life. Most prominant amongst these are reductions in the size of seed and embryo, and the lack of differentiation of the embryo at maturity. The number of seeds produced by each flower is typically very large and the shape, structure and surface features of seeds involving adaptation for wind dispersal show remarkable parallels in many species. Specific adaptations for zoochory are rare but well developed in a small number of genera, some of which produce scents like fungal fruit bodies or floral parts which mimic fungal sporocarps. Vegetative parts are often even more conspicuously reduced. Most myco‐heterotrophs are entirely subterranean for most of their lives and these stages exhibit adaptations consistent with a change in function from organs of absorption to organs of storage, shown by the almost universal loss of root hairs, decrease in surface area as exhibited in short cylindric‘vermiform’and tuberous roots or, in extreme cases, the complete suppression of roots and the formation of a swollen tuber or rhizome. Increased width of the root cortex often accommodates mycorrhizal infection and stores of carbohydrates and other materials obtained from the fungal symbiont. Mycorrhizal infection is confined to the below‐ground parts of the plants but may be found there in modified stems as well as in roots. In many genera, stems are exceptionally slender and thread‐like and their vascular tissues are either reduced to a single narrow cylinder of bicollateral bundles or, minimally, to four or six narrow bundles in the cortex. Secondary thickening is poorly developed in all but a tiny minority of species, lignification being confined to annular or, rarely, a few scalariform xylem vessels. Phloem is present in very small amounts and then mainly as parenchyma with sieve tubes frequently recorded as narrow and possibly with abherent sieve plates. Leaves are typically reduced to widely spaced achlorophyllous scales on the inflorescence axis. Occasionally, they are present only on underground rhizomes or tubers. The vascular supply to the leaf‐scales, normally reduced to a single trace, may be ab...

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Recent Advances in Botany, Propagation, and Physiology of Orchids

Sheehan

1983

Horticultural Reviews

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Atmospheric condition controlling the seed germination of an achlorophyllous orchid,Galeola septentrionalis

Cited by 23 publications

References 2 publications

Tansley Review No. 110.

Tansley Review No. 110.

The biology of myco‐heterotrophic (‘saprophytic’) plants

Recent Advances in Botany, Propagation, and Physiology of Orchids

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