Evolution and Systematics
Functional Adaptations
Functional adaptation
Leaves protect from the elements: conifers
"Some species of tree, even outside the balmy climates of the tropics, manage to produce a kind of leaf that can survive both drought and cold. Conifers do so. Many of them grow branches that, instead of rising upwards towards the sky, slope gently downwards. In consequence, snow tends to slide off them and does not accumulate into huge loads that might break them. Their leaves are not flat and broad but needle-shaped. They have a thick waxy rind, very little freezable sap, and pores that are set in the bottom of a deep groove running the length of the needle." (Attenborough 1995:88-89)
Learn more about this functional adaptation.
The leaves of conifers protect from drought, snow and cold by employing unique design elements, including a needle shape, thick waxy rinds, and pores set in deep grooves in the needles.
"Some species of tree, even outside the balmy climates of the tropics, manage to produce a kind of leaf that can survive both drought and cold. Conifers do so. Many of them grow branches that, instead of rising upwards towards the sky, slope gently downwards. In consequence, snow tends to slide off them and does not accumulate into huge loads that might break them. Their leaves are not flat and broad but needle-shaped. They have a thick waxy rind, very little freezable sap, and pores that are set in the bottom of a deep groove running the length of the needle." (Attenborough 1995:88-89)
Learn more about this functional adaptation.
- Attenborough, D. 1995. The Private Life of Plants: A Natural History of Plant Behavior. London: BBC Books. 320 p.
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Functional adaptation
Transport system prevents spread of embolisms: conifers
"The tracheids in conifers have a specialised arrangement of fail-safe valves in the thin-walled pit areas. The pit pairs themselves are more or less circular in surface view. The cell wall bulges out on either side of the thin membrane between the cells (a laminate -- cell wall, middle lamella, cell wall). The aperture in the out-bulging part of the wall is narrower than the diameter of the central membrane. The central membrane has an annular rim which is not thickened, but the centre of the membrane has a thickenened area. This gives a bordered appearance to the pit pair (Fig. 4).
"If there is a failure of the water column in a tracheid, the thickened portion of the pit membrane moves across under the differential pressure, blocking the pit aperture, and helping prevent the spread of an embolism." (Cutler 2005:100)
Learn more about this functional adaptation.
The tracheids in conifers prevent the spread of an embolism using fail-safe valves in their pit membranes.
"The tracheids in conifers have a specialised arrangement of fail-safe valves in the thin-walled pit areas. The pit pairs themselves are more or less circular in surface view. The cell wall bulges out on either side of the thin membrane between the cells (a laminate -- cell wall, middle lamella, cell wall). The aperture in the out-bulging part of the wall is narrower than the diameter of the central membrane. The central membrane has an annular rim which is not thickened, but the centre of the membrane has a thickenened area. This gives a bordered appearance to the pit pair (Fig. 4).
"If there is a failure of the water column in a tracheid, the thickened portion of the pit membrane moves across under the differential pressure, blocking the pit aperture, and helping prevent the spread of an embolism." (Cutler 2005:100)
Learn more about this functional adaptation.
- Cutler, DF. 2005. Design in plants. In: Collins, MW; Atherton, MA; Bryant, JA, editors. Nature and Design. Southampton, Boston: WIT Press. p 95-124
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Molecular Biology and Genetics
Molecular Biology
Statistics of barcoding coverage
Barcode of Life Data Systems (BOLD) Stats
| Specimen Records: | 3,895 | Public Records: | 2,796 |
| Specimens with Sequences: | 6,022 | Public Species: | 623 |
| Specimens with Barcodes: | 4,352 | Public BINs: | 0 |
| Species: | 688 | ||
| Species With Barcodes: | 671 | ||
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Barcode data
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Locations of barcode samples
Collection Sites: world map showing specimen collection locations for Pinophyta

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