Thistle is the common name of a group of flowering plants characterised by leaves with sharp prickles on the margins, mostly in the family Asteraceae. Prickles can also occur all over the plant â on the stem and on the flat parts of the leaves. These prickles are an adaptation that protects the plant from being eaten by herbivores. Typically, an involucre with a clasping shape similar to a cup or urn subtends each of a thistle's flower heads. The typically feathery pappus of a ripe thistle flower is known as thistle-down. The comparative amount of spininess varies dramatically by species. For example, Cirsium heterophyllum has minimal spininess while Cirsium spinosissimum is the opposite.
圖片編號:
283380069
拍攝者:
Elrondperedhil
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授權類型 | 尺寸 | 像素 | 格式 | 點數 | |
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標準授權 | XS | 480 x 320 | JPG | 13 | |
標準授權 | S | 800 x 533 | JPG | 15 | |
標準授權 | M | 2121 x 1414 | JPG | 18 | |
標準授權 | L | 2738 x 1825 | JPG | 20 | |
標準授權 | XL | 3464 x 2309 | JPG | 22 | |
標準授權 | MAX | 5184 x 3456 | JPG | 23 | |
標準授權 | TIFF | 7331 x 4888 | TIF | 39 | |
進階授權 | WEL | 5184 x 3456 | JPG | 88 | |
進階授權 | PEL | 5184 x 3456 | JPG | 88 | |
進階授權 | UEL | 5184 x 3456 | JPG | 88 |
XS
S
M
L
XL
MAX
TIFF
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標準授權 | 480 x 320 px | JPG | 13 點 |
標準授權 | 800 x 533 px | JPG | 15 點 |
標準授權 | 2121 x 1414 px | JPG | 18 點 |
標準授權 | 2738 x 1825 px | JPG | 20 點 |
標準授權 | 3464 x 2309 px | JPG | 22 點 |
標準授權 | 5184 x 3456 px | JPG | 23 點 |
標準授權 | 7331 x 4888 px | TIF | 39 點 |
進階授權 | 5184 x 3456 px | JPG | 88 點 |
進階授權 | 5184 x 3456 px | JPG | 88 點 |
進階授權 | 5184 x 3456 px | JPG | 88 點 |