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lichenmore about lichen

lichen


  2  definitions  found 
 
  From  Webster's  Revised  Unabridged  Dictionary  (1913)  [web1913]: 
 
  Lichen  \Li"chen\  (l[imac]"k[e^]n;  277),  n.  [L.,  fr  Gr 
  leichh`n.] 
  1.  (Bot.)  One  of  a  class  of  cellular,  flowerless  plants, 
  (technically  called  {Lichenes}),  having  no  distinction  of 
  leaf  and  stem,  usually  of  scaly,  expanded,  frond-like 
  forms,  but  sometimes  erect  or  pendulous  and  variously 
  branched.  They  derive  their  nourishment  from  the  air,  and 
  generate  by  means  of  spores.  The  species  are  very  widely 
  distributed,  and  form  irregular  spots  or  patches,  usually 
  of  a  greenish  or  yellowish  color,  upon  rocks,  trees,  and 
  various  bodies,  to  which  they  adhere  with  great  tenacity. 
  They  are  often  improperly  called  {rock  moss}  or  {tree 
  moss}. 
 
  Note:  A  favorite  modern  theory  of  lichens  (called  after  its 
  inventor  the  Schwendener  hypothesis),  is  that  they  are 
  not  autonomous  plants,  but  that  they  consist  of 
  ascigerous  fungi,  parasitic  on  alg[ae].  Each  lichen  is 
  composed  of  white  filaments  and  green,  or  greenish, 
  rounded  cells,  and  it  is  argued  that  the  two  are  of 
  different  nature,  the  one  living  at  the  expense  of  the 
  other  See  {Hyph[ae]},  and  {Gonidia}. 
 
  2.  (Med.)  A  name  given  to  several  varieties  of  skin  disease, 
  esp.  to  one  characterized  by  the  eruption  of  small 
  conical  or  flat,  reddish  pimples,  which  if  unchecked, 
  tend  to  spread  and  produce  great  and  even  fatal 
  exhaustion. 
 
  From  WordNet  r  1.6  [wn]: 
 
  lichen 
  n  :  any  thallophytic  plant  of  the  division  Lichenes;  occur  as 
  crusty  patches  or  bushy  growths  on  tree  trunks  or  rocks 
  or  bare  ground  etc 




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