Alismac&t — Sagitiaria.  465

1.  S.  BarjUtiffAia  (fig.  225).  Arrow-head.— This  ib  the  only
e  tliat  need  occupy  our  attention.  It.  is  a  common  plant  in
o  South  of  England,  about  a  foot  high,  with  ephemeral  uni-


Vii.m.  S^Uaria  Hglwrallk.    (jnnt,  ilu'.!

Eexual  flowers  an  inch  or  more  in  diameter,  white  with  a  purple
centre.  Segments  of  the  perianth  all  similar  ;  stamens  nume-
rous.    It  blooms  throughout  the  Summer.
2.  BOTOSIUS.
This  is  a  genus  comprising  one  or  two  very  elegant  aquatic
plants  with  slender  erect  triquetrous  leaves  and  a  tall  scape
surmounted  by  a  large  umbel  of  rosy-pink  flowers.  Perianth-
segments  free,  equal,  all  coloured.  Stamens  9.  Carpels  about
6,  many-seeded.  The  derivation  of  the  generic  name  is  ob-
scure.
1 .  B.  wmbeil^tue.  Flowering  Rush. — One  of  our  handsomest
native  aquatics  and  the  only  British  plant  having  9  stamens.
It  grows  from  3  to  6  feet  high  according  to  conditions,  and
flowers  at  Midsummer.
AponogHon  distdckyus  is  a  handsome  aquatic  plant,  re-
markable for  ita  floating  branched  spikes  of  small  fragrant
bracteate  white  flowers.  Leaves  oblong-lanceolate,  on  long
petioles,  floating.  This  plant  is  a  native  of  the  Cape  of  Oooil
Hope,  but  it  will  flourish  in  a  lake  or  stream  if  planted  at  a


4-66  Orckidacetr.
depth  of  about  2  feet  of  water.  It  belongs  to  a  small  prder
called  Juiuyi^mace^Ef  distinguished  from  Aliam&ceas  by  the
apetalous  bracteate  flowers,

Obdbb  VI.— OECHIDiORffi.
Terrestrial  herbs   with   tuberous    or    fascicled    roots    aud
eheatbing  radical  or  sessile  cauline  leaves ;  or,  aa  in  moat  of
■  the   tropical   species,  epiphytes,  with   enlarged  stems   called
pseudo-bulbs.    Flowers  solitary,  spicate,  racemose  or  paniculate.
Perianth  coloured,  superior,  composed  of  6  irregular  segments.
