﻿144 
  KEY 
  AND 
  FLORA 
  

  

  52. 
  RUTACEJE. 
  RUE 
  FAMILY 
  

  

  Shrubs 
  or 
  trees. 
  Leaves 
  alternate, 
  compound, 
  without 
  stip- 
  

   ules, 
  marked 
  with 
  translucent 
  dots. 
  Flowers 
  usually 
  actino- 
  

   morphic. 
  Sepals 
  and 
  petals 
  3-5 
  or 
  none 
  ; 
  petals 
  hypogynous 
  

   or 
  perigynous 
  when 
  present. 
  Stamens 
  as 
  many 
  or 
  twice 
  as 
  

   many 
  as 
  the 
  sepals, 
  inserted 
  on 
  the 
  glandular 
  disk. 
  Pistils 
  

   2-5, 
  often 
  partially 
  united. 
  Fruit 
  a 
  capsule, 
  a 
  key 
  fruit, 
  or 
  in 
  

   the 
  important 
  genus 
  Citrus 
  (orange, 
  lemon, 
  lime, 
  etc., 
  not 
  here 
  

   described) 
  a 
  leathery-skinned 
  berry, 
  the 
  outer 
  part 
  of 
  the 
  skin 
  

   containing 
  many 
  spherical 
  oil 
  cavities.* 
  

  

  I. 
  XANTHOXYLUM 
  

  

  Trees 
  or 
  shrubs 
  ; 
  bark, 
  twigs, 
  and 
  petioles 
  usually 
  prickly 
  ; 
  

   leaves 
  odd-pinnate, 
  marked 
  with 
  translucent 
  dots. 
  Flowers 
  in 
  

   axillary 
  or 
  terminal 
  cymes 
  or 
  umbels, 
  monoecious 
  or 
  dioecious. 
  

   Sepals 
  and 
  petals 
  3-5 
  or 
  none. 
  Stamens 
  3-5, 
  hypogynous. 
  

   Pistils 
  2-5, 
  distinct. 
  Carpels 
  2-valved, 
  1-2-seeded 
  ; 
  seeds 
  

  

  smooth 
  and 
  shining.* 
  

  

  

  

  1. 
  X. 
  americanum 
  Mill. 
  NORTHERN 
  PRICKLY 
  ASH, 
  TOOTHACHE 
  

   TREE. 
  A 
  prickly 
  shrub, 
  8-12 
  ft. 
  high, 
  with 
  aromatic 
  bark. 
  Leaves 
  

   pinuately 
  compound 
  ; 
  leaflets 
  ovate-oblong. 
  Flowers 
  small 
  and 
  

   greenish, 
  in 
  axillary 
  umbels, 
  appearing 
  before 
  the 
  leaves. 
  Petals 
  

   4-5. 
  Pistils 
  3-5, 
  the 
  styles 
  slender. 
  Pods 
  rather 
  globose, 
  somewhat 
  

   more 
  than 
  \ 
  in. 
  in 
  diameter, 
  roughish, 
  borne 
  on 
  a 
  short 
  stalk 
  above 
  

   the 
  receptacle, 
  with 
  a 
  strong 
  scent 
  of 
  lemon 
  and 
  tasting 
  at 
  first 
  aro- 
  

   matic, 
  then 
  burning. 
  Rocky 
  woods, 
  ravines, 
  and 
  river 
  banks. 
  

  

  II. 
  PTELEA 
  L. 
  

  

  Shrubs 
  with 
  smooth 
  and 
  bitter 
  bark. 
  Leaves 
  with 
  3 
  leaflets. 
  

   Flowers 
  in 
  terminal 
  cymes, 
  somewhat 
  monoecious. 
  Sopals 
  3-6, 
  

   deciduous, 
  much 
  shorter 
  than 
  the 
  petals. 
  Stamens 
  4-5, 
  longer 
  

   than 
  the 
  petals 
  and 
  alternate 
  with 
  them. 
  Pistillate 
  flowers 
  

   producing 
  imperfect 
  stamens. 
  Ovary 
  compressed, 
  2-celled. 
  

   Fruit 
  a 
  2-celled, 
  2-seeded, 
  broadly 
  winged 
  key.* 
  

  

  1. 
  P. 
  trifoliate 
  L. 
  HOP 
  TREE, 
  WAFER 
  ASH. 
  A 
  shrub 
  4-8 
  ft. 
  high. 
  

   Leaves 
  long-petioled 
  ; 
  leaflets 
  oval 
  or 
  ovate, 
  acute, 
  obscurely 
  serrate, 
  

  

  

  