lumë ("river") is native, as is rrymë (the flow of river water). Words for smaller streams and stagnant pools of water are more often native, but the word for "pond", pellg is in fact a semantically shifted descendant of the old Greek word for "high sea", suggesting a change in location after Greek contact. Albanian has maintained since Proto-Indo-European a specific term referring to a riverside forest (gjazë), as well as its words for marshes. Curiously, Albanian has maintained native terms for "whirlpool", "water pit" and (aquatic) "deep place", leading Orel to speculate that the Albanian Urheimat likely had an excess of dangerous whirlpools and depths. However, all the words relating to seamanship appear to be loans. Vegetation Regarding forests, words for most conifers and shrubs are native, as are the terms for "alder", "elm", "oak", "beech", and "linden", while "ash", "chestnut", "birch", "maple", "poplar", and "willow" are loans. Social organization The original kinship terminology of Indo-European was radically reshaped; changes included a shift from "mother" to "sister", and were so thorough that only three terms retained their original function; the words for "son-in-law", "mother-in-law" and "father-in-law". All the words for second-degree blood kinship, including "aunt", "uncle", "nephew", "niece", and terms for grandchildren, are ancient loans from Latin. Linguistic contacts Overall patterns in loaning Openness to loans has been called a "characteristic feature" of Albanian. The Albanian original lexical items directly inherited from Proto-Indo-European are far fewer in comparison to the loanwords, though loans are considered to be "perfectly integrated" and not distinguishable from native vocabulary on a synchronic level. Although Albanian is characterized by the absorption of many loans, even, in the case of Latin, reaching deep into the core vocabulary, certain semantic fields nevertheless remained more resistant. Terms pertaining to social organization are often preserved, though not those pertaining to political organization, while those pertaining to trade are all loaned or innovated. While the words for plants and animals characteristic of mountainous regions are entirely original, the names for fish and for agricultural activities are often assumed to have been borrowed from other languages. However, considering the presence of some preserved old terms related to the sea fauna, some have proposed that this vocabulary might have been lost in the course of time after proto-Albanian tribes were pushed back into the inland during invasions. Wilkes holds that the Slavic loans in Albanian suggest that contacts between the two