The onion has been grown and selectively bred in cultivation for at least 7,000 years. It is a biennial plant, but is usually grown as an annual. Modern varieties typically grow to a height of 15 to 45 cm 6 to 18 in. The leaves are yellowish- to bluish green and grow alternately in a flattened, fan-shaped swathe. They are fleshy, hollow, and cylindrical, with one flattened side. They are at their broadest about a quarter of the way up, beyond which they taper to blunt tips. The base of each leaf is a flattened, usually white sheath that grows out of the basal plate of a bulb. From the underside of the plate, a bundle of fibrous roots extends for a short way into the soil. As the onion matures, food reserves begin to accumulate in the leaf bases and the bulb of the onion swells.
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244816373
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Rantony1184
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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 | 296 x 480 | JPG | 13 | |
標準授權 | S | 493 x 800 | JPG | 15 | |
標準授權 | M | 1359 x 2207 | JPG | 18 | |
標準授權 | L | 1754 x 2849 | JPG | 20 | |
標準授權 | XL | 2347 x 3811 | JPG | 22 | |
標準授權 | MAX | 2718 x 4414 | JPG | 23 | |
標準授權 | TIFF | 3319 x 5390 | TIF | 39 | |
進階授權 | WEL | 2718 x 4414 | JPG | 88 | |
進階授權 | PEL | 2718 x 4414 | JPG | 88 | |
進階授權 | UEL | 2718 x 4414 | JPG | 88 |
XS
S
M
L
XL
MAX
TIFF
WEL
PEL
UEL
標準授權 | 296 x 480 px | JPG | 13 點 |
標準授權 | 493 x 800 px | JPG | 15 點 |
標準授權 | 1359 x 2207 px | JPG | 18 點 |
標準授權 | 1754 x 2849 px | JPG | 20 點 |
標準授權 | 2347 x 3811 px | JPG | 22 點 |
標準授權 | 2718 x 4414 px | JPG | 23 點 |
標準授權 | 3319 x 5390 px | TIF | 39 點 |
進階授權 | 2718 x 4414 px | JPG | 88 點 |
進階授權 | 2718 x 4414 px | JPG | 88 點 |
進階授權 | 2718 x 4414 px | JPG | 88 點 |