ash (n.2)youdaoicibaDictYouDict[ash 词源字典]
type of tree, Old English æsc "ash tree," also "spear made of ash wood," from Proto-Germanic *askaz, *askiz (cognates: Old Norse askr, Old Saxon ask, Middle Dutch esce, German Esche), from PIE root *os- "ash tree" (cognates: Armenian haci "ash tree," Albanian ah "beech," Greek oxya "beech," Latin ornus "wild mountain ash," Russian jasen, Lithuanian uosis "ash"). Ash was the preferred wood for spear-shafts, so Old English æsc sometimes meant "spear" (as in æsc-here "company armed with spears").[ash etymology, ash origin, 英语词源]
birch (n.)youdaoicibaDictYouDict
Old English berc, beorc (also the name of the rune for "b"), from Proto-Germanic *berkjon (cognates: Old Saxon birka, Old Norse börk, Danish birk, Swedish björk, Middle Dutch berke, Dutch berk, Old High German birihha, German Birke), from PIE *bhergo (cognates: Ossetian barz, Old Church Slavonic breza, Russian bereza, Lithuanian beržas, Sanskrit bhurjah, Latin farnus, fraxinus "mountain ash"), from root *bhereg- "to gleam, white." Meaning "bunch of birch twigs used for flogging" (1640s) led to verb meaning "to flog" (1830). Related: Birched; birching. Birch beer is by 1827, American English.
rowan (n.)youdaoicibaDictYouDict
"mountain ash," 1804, from rowan-tree, rountree (1540s), northern English and Scottish, from a Scandinavian source (compare Old Norse reynir, Swedish Ronn "the rowan"), ultimately from the root of red, in reference to the berries.
There were those in this neighbourhood, long after the beginning of the present century, who believed that a slip of rowan tree carried on their person dispelled glamour, and rendered nugatory all the powers of sorcery and witchcraft. [Alexander Laing, "Lindores Abbey and the Burgh of Newburgh," Edinburgh, 1876]
sorb (n.)youdaoicibaDictYouDict
"fruit of the service tree," 1520s, from French sorbe, from Latin sorbum "service-berry" (small, edible fruit of the European mountain ash), from sorbus, of uncertain origin.
sorbic (adj.)youdaoicibaDictYouDict
1815, in sorbic acid, so called because it was first isolated from the berries of the mountain ash (see sorb).