488 



BOTANY 



All the pollen -grains of each theca are usually united by a viscid 

 substance into a club-shaped mass or pollinium (e), attached above 



or below to a mucilaginous filament 

 termed the CAUDICLe (e, r). In a 

 few cases several pollinia are present. 

 The three-lobed stigma (b, h) is 

 situated directly below the anther. 

 The two lateral lobes are always 

 normally developed and destined to 

 receive the pollen, while the anterior 

 lobe has frequently the form of a 

 pouch-shaped beak or eostellum 

 (b, I), in which one or two small 

 masses of sticky mucilage (q), the 

 glandule (retinacida), are formed 

 by the disorganisation of the tissue. 

 To these sticky glandulse are 

 attached the caudicles with their 

 pollinia. The whole structural de- 

 velopment of the flower represents 

 an adaptation to insect-pollination. 

 When an insect inserts its proboscis 

 in the nectaries of the labellum, the 

 glandulse with their stalked pollinia 

 become glued to it, and the pollen 



the labellum : 7i, stigma ; I, rostellmn ; 7c, 

 tooth-like prolongation of the rostellum ; 

 m, anther ; n, connective ; o, pollinium ; q, 

 glandula ; $>, staminodium. c, A pollinium : 

 r, caudicle ; s, pollen, d, Ovary in trans- 

 verse section. (After Berg and Schmidt.) 



Fig. 432. — Orchis militaris. a, Flower : 

 bract ; 6, ovary ; e, the outer, and d, the 

 two anterior inner perigone leaves ; e, ; label- 

 luni with the spur/; g, gynostemium. b, 

 Flower after removal of all of the perigone 

 leaves with exception of the upper part of is thus applied to the next flower 



visited by the insect. Similarly, 

 by inserting a pointed instrument 

 in the spur, a lead-pencil for ex- 

 ample, the pollinia will be found 

 attached to it on its withdrawal. 



The capsule is often leathery, and in dehiscing splits into six valves. 



The embryo is usually spherical and exhibits no differentiation into 



hypocotyl and cotyledon. 



Many of the indigenous species have underground tubers (e.g. Orchis). As a 

 rule, two tubers are present, formed by the union of several roots ; according as 

 the coalescence is more or less complete, they are ovate and smooth (Fig. 434), or 

 palmately divided (Fig. 433). One of the tubers, the older mother-tuber, is dark- 

 coloured and flaccid ; it bears the floral shoot and afterward dies. The other, the 

 daughter-tuber, is firmer, lighter-coloured, and provided with an apical bud. It 

 remains dormant in the soil over winter, and in the succeeding spring gives rise 

 to an aerial shoot, and then, after producing a new daughter-tuber, acquires in 

 turn the structure and appearance of a mother-tuber in consequence of the exhaus- 

 tion of the accumulated reserve material of its cells. 



Sub-Families and Representative Genera. — (1) Diandrae. Two (rarely 

 three) fertile stamens. All three stigmatic lobes susceptible of pollination. 

 Cypripedium. (2) Monandrae. One fertile stamen. Of the three stigmatic lobes, 



