AXACHAMS.] HYDROCHARIDE^E. 351 



nodes. Leaves ^ J in., sessile, acute, margined. Flowers resting on the 

 surface of the water, \ in. diam., greenish-purple, tube of female 4-8 in., 

 capillary. Sepals boat-shaped. Petals recurved. Stigmas long, terete, 

 notched. Male not hitherto found in England. DISTRIB. N. America. 



ORDER II. ORCHID'EJE. 



Terrestrial herbs, roots fascicled or tuberous (many exotics are epiphytes, 

 with pseudo-bulbs). Leaves sheathing at the base, or scales. Flowers 

 solitary, spiked, racemed or panicled. Perianth superior, irregular, of 6 

 coloured segments ; 3 outer (sepals] nearly similar ; 3 inner lateral (petals) 

 like the sepals ; lower inner (lip) dissimilar, usually larger, often spurred. 

 Stamens confluent with the style into an unsymmetrical column ; anther 

 1 opposite the lip (in Cypripedium 2 opposite the petals), 2-celled, per- 

 sistent or deciduous ; pollen in 2, 4, or 8 pyriform pedicelled masses 

 (pollinia), pedicels (caudides) terminating iu a gland ; glands exposed or 

 in 1 or 2 pouches. Ovary usually long and twisted, 3-gonous, 1 -celled ; 

 style often terminating in a beak (rostellum) at the base of the anther, 

 stigma a viscid surface (of three confluent stigmas) facing the lip, beneath 

 the rostellum, rarely 2-lobed ; ovules very many, anatropous, placentas 

 3 parietal. Capsule 3-valved, valves separating from 3 septa. Seeds innu- 

 merable, very minute, fusiform, testa very lax reticulate, albumen ; 

 embryo fleshy. DISTRIB. All climates and situations but maritime and 

 aquatic; genera 400; species 3,000. AFFINITIES. With Iridece. PRO- 

 PERTIES. A few are aromatic (Vanilla): the tubers of Orchis are nutritive, 

 and yield starch and salep. 



TRIBE I. OPH'RYDE.ffi. Anther 1, confluent with the face of the style ; 

 cells 2, bursting vertically ; pollen-masses 2, free or united by their glands, 

 of many grains united by an elastic web. 



* Lip spurred. Stigma a depressed surface. 



Pollen-glands free or connate, in one pouch 1. Orchis. 



Pollen-glands free, exposed. Flowers purple 2. Gymnadenia. 



Pollen-glands free, exposed. Flowers white or green 3. Habenaria. 



**Spur very short, stigma of two oblong lobes 4. Neotinea. 



*** Spur none. 



Pollen-glands both in one pouch 5. Aceras. 



Pollen-glands exposed 6. Herminium. 



Pollen-glands in two pouches 7. Ophrys. 



TRIBE II. ARETHU'SEJE. Anther a deciduous 2-celled cap, crowning 

 the column ; pollen-masses 2, free or united by their glands, of free 



grains, hence powdery 8. Epipogium. 



TRIBK III. NEOT"TIDEJE. Anther a deciduous 2-celled cap hinged to the 

 top or back of the column ; pollen-masses 2 or 4, grains waxy or powdery 

 united by an elastic web. 

 Lateral sepals and petals spreading, tips incurved. 



* Upper lobe of lip concave, lower entire. 



Flowers racemed drooping ; ovary straight 9. Epipactis. 



Flowers spiked, suberect ; ovary twisted 10. Cephalanthera. 



