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Let's Talk Stomata (photos)
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Posted by theforestprimeval (My Page) on Sat, Oct 31, 09 at 4:01
| Fitzroya cupresoides Seedling, showing white stomatal lines on cotyledons...
Fitzroya cupressoides foliage with female cones (I believe almost all plants in the United States are clones from the same individual female...)
One of the two Acmopyle Species, showing heavy stomatal white lines....
Athrotaxis selaginoides Seedlings, showing white stomatal lines (very beautiful)...
More Acmopyle... this is new growth not stomata, but still very beautiful and oddly purple...
Not to mention the many more that show bold white stomata...Thujopsis dolobrata, Austrocedrus chilensis, some Agathis species. Very beautiful..my only question...why? Please answer and/or post other pictures showing this phenomenon. |
Follow-Up Postings:
RE: Let's Talk Stomata (photos)
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| Stomatal bands are used by a plant for air/gaseous exchange. I think... Dax |
RE: Let's Talk Stomata (photos)
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| I guess more specfically I meant to say...why are they sometimes white in various species? Its protective resin, I would assume, but not sure. The method that stomata have of opening and closing and how it corresponds to turgor pressure and water availability also seems quite fascinating. I'm hoping somebody will put forth some good info on this as my depth of knowledge on this subject is pretty lacking. |
RE: Let's Talk Stomata (photos)
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| Not an absolute correlation, but as a general rule, species with leaves glaucous blue-green all over (e.g. Picea pungens, Cupressus glabra, Pinus monophylla) come from dry climates, with the stomatal wax acting as a water conservation feature; conversely, species with glossy green above, vivid white below (e.g. Abies koreana, A. forrestii, Picea brachytyla) come from temperate rainforest climates, with the glossy top to shed rain, and thick white wax to keep excess water out. The wettest climate conifers (e.g. Abies delavayi, A. densa) have the sides of the needles curved down to act as a further water barrier. There are exceptions, e.g. Pinus johannis with leaves glossy green outer face, white inner sides, but is from a dry climate. The odd colour of the young Acmopyle shoots is likely related to disguise - if they look half-dead and unappetising, they are less attractive to browsing animals (including sap-sucking insects, etc.). Saw some research a few years ago which demonstrated that woody plants with drooping, non-green new foliage like this suffered distinctly less predation of their tender new foliage. Resin |
RE: Let's Talk Stomata (photos)
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| Recently I saw this info related to transpiration rate and water loss.....not specifically addressing your stomata question but affecting turgor pressure in some evergreen species for sure. " ...The morphological differences between awl-shaped juvenile needles and scalelike adult needles in junipers is linked to a suite of physiological traits that favors establishment of juveniles and persistence of adults (Miller et al. 1995). Juvenile foliage requires less energy to produce, and its characteristics of high rates of CO2 assimilation and transpiration and lower investment of biomass and nitrogen per unit area enhance establishment and early growth. However, high rates of CO2 uptake and traspriation cause high rates of water loss, which are not sustainable for the adult tree in the dry native envionment of junipers of eastern and western North America. Therefore, the conservative use of water and nitrogen resources associated with adult scalelike foliage is a successful stress-tolerant strategy of the adult trees. (From Michigan Trees, A Guide to the Trees of the Great Lakes Region, Barnes and Wagner, 2004) Have any of you found ornamental juniper cultivars that retain juvenile needle growth when older to have higher water needs? And here's a stomata chuckle: Parent: What did you learn about at school today? Child: We learned about stomata. Parent: What's stomata? Child: I don't know. What's stomata with you? Groan..... |
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