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单词 megaphyll
释义

megaphylln.

Brit. /ˈmɛɡəfɪl/, U.S. /ˈmɛɡəˌfɪl/
Origin: Formed within English, by compounding. Etymons: mega- comb. form, -phyll comb. form.
Etymology: < mega- comb. form + -phyll comb. form, in sense 2 after Danish megafyl (C. Raunkiaer 1917, in Bot. Tidsskrift 34 229). Compare earlier megaphyllous adj., microphyll n., megaphylly n.
Botany.
1. A type of leaf, found in ferns and some higher plants, which is usually large and has a complex vascular system with leaf gaps in the stem stele. Opposed to microphyll.
ΘΚΠ
the world > plants > part of plant > leaf > [noun] > other types of leaf
ear leaf1835
microsporophyll1888
megaphyll1908
microphyll1908
megaphyll1918
1908 New Phytologist 7 125 There is no evidence of any capacity of the microphyll to evolve into the megaphyll.
1932 Proc. Linn. Soc. 145 26 There is an early differentiation between..the simple microphylls and the branch systems or ‘telomes’ which later evolved into the megaphylls of the higher plants.
1947 Philos. Trans. (Royal Soc.) B. 232 353 In the ferns as a class the leaves, or megaphylls, are large in proportion to the shoot on which they are borne.
1961 Amer. Jrnl. Bot. 48 541 The occurrence of microphylls on the entire branching systems of plants lacking clearly delimited stems and megaphylls is regarded as primitive.
1989 Plant Systematics & Evol. 165 147 It is striking that there is nothing particularly primitive or pre-fern about these plants, they have all the assets of modern Filicalean ferns with bilaterally organized megaphylls and biseriate pinnae.
2. Chiefly Ecology. In the Raunkiaer system of leaf-size classification: a very large leaf with a surface area greater than 1640 square centimetres.
ΘΚΠ
the world > plants > part of plant > leaf > [noun] > other types of leaf
ear leaf1835
microsporophyll1888
megaphyll1908
microphyll1908
megaphyll1918
1918 G. D. Fuller & A. L. Bakke tr. C. Raunkiaer in Plant World 21 29 I have decided upon six ‘six-classes’ proceeding from the smallest to the largest blade, and have given them the following names which may be used as adjectives as well as nouns: Leptophyll, Nanophyll, Microphyll, Mesophyll, Macrophyll, and Megaphyll.
1932 Ecology 13 22 Raunkiaer's classes of leaf sizes are used, the following being the size limits:..Megaphyll: over 164,025 sq. mm.
1952 Jrnl. Ecol. Oct. 303 Table 11 shows the percentages of species and individuals falling into the leaf-size classes proposed by Raunkiaer... Megaphyll.
1976 Jrnl. Ecol. 64 938 The largest leaf sizes, macro- and megaphyll..were absent or infrequent in the drier forests.
1993 Jrnl. Ecol. 80 696 Leaf category..Megaphyll..% individuals..7.1.
This entry has been updated (OED Third Edition, June 2001; most recently modified version published online March 2022).
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n.1908
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