PLATE IX— COMMON ORCHIS (Orchis mascula). 



Orchids are remarkable, in many respects, for the curious shapes of the flowers, the peculiar structure of their parts, and the 

 numerous and beautiful contrivances for cross-fertilisation. The common or purple Orchis occurs in shady situations, and flowers early 

 in April. The underground stem is in the form of a Tuber, which in this species is ovoid, or it may be divided at the base into 

 finger-like processes. There are two Tubers, a young one storing up material for next year, while the old one is providing for the 

 present The young Tuber arises as a lateral bud, growing in size as the old one decays, and thus the plant is carried on from year 

 to year. The flower and its arrangement will be noticed in connection with the Figures. 



As the Orchid ends the Monocotyledons, space has been found to show the germination of the Date. The Date belongs to the 

 Palm family, but is here introduced to show the well-developed primary or tap-root, a structure with which Monocotyledons are not 

 usually credited. 



Root and Stem — 



Fig. 1. Dig up Tubers at various seasons, before, during, and after flowering, and examine. 



The old Tuber is shrivelled, and dark in colour, while the young one is firmer and paler. The relative sizes 

 will vary according to the time at which they are dug up. 



Root-fibres arise from the base of the flowering stem, and are thus adventitious. 

 Fig". 2. Vertical section of Tuber preserved in spirit 



The old Tuber lies beneath flowering stem, and has been pretty largely drained of its substance to afford 

 nourishment to it, as well as to give rise to the young Tuber. 



The young Tuber is now plump and in good condition, and bears a bud at its summit, which is a prepara- 

 tion for the flowering stem of next year. The young Tuber, at least in its early stages, exhibits indications of its 

 first root at the base, but the future rapid growth of the tuber causes this primary root to disappear. 

 Flower — 



Fig. 3. Flower in front view. 



Sepals, three, one median and two lateral. 



Petals, three, the lower one forming a platform on which insects may alight. 

 Stamen, one, and Anther two-lobed. 



Stigmas, three, two lateral and one median, modified into the Rostellum (Lat a little beak). 

 Ovary, beneath and not seen in this view. 

 Fig. 4. Remove sepals and two of the petals, so as to expose central portion of flower; a and b show the essential organs and 

 their relative positions. 



Anther-lobes open lengthways, exposing the pollen-masses, and there is a Connective between, which arches 

 over at the top. 

 Fig. 5. Make a vertical section of the flower used in Fig. 4. 



The relative position and structure of the parts have evidently reference to the visits of insects. The 

 entrance to the spur is guarded by the Rostellum, in which, as in a cup, lies the Sticky base of each pollen-mass. 

 The stigmatic surfaces project immediately beneath and by the side of rostellum, so that the upright pollen-mass, 

 when it becomes horizontal on the insect's head, will strike against it. 

 Diagram of the unopened flower — 



(a.) Orchid — Calyx of three coloured Sepals. 



Corolla of three coloured Petals, alternating with sepals. 



Androecium of one Stamen, the so-called Auriculas on each side of it representing Staminodes. 

 Gyncecium of three united Carpels. 

 (b.) Lady's Slipper or Cypripedium is distinguished by having two Anthers, not, however, corresponding to any of 

 those in Orchis, but from their position forming two of an inner whorl of stamens. 

 A comparison of Lady's Slipper with other Orchids, and a consideration of monstrous flowers, has led to the 

 view that the original type of Orchid flower was one in which there were_six Perianth-segments and six Stamens in 

 two whorls, as represented by the formula Ca. 3, Co. 3, An. 3 + 3, Gn. (3). 

 Foliage- and Floral- Leaves — 



Fig. 6. Foliage-leaf, with parallel veins, and shining surface spotted with dark purple. 

 Fig. 7. Bract coloured, with central nerve, broad base, and pointed tip. 

 Fig. 8. Sepal, blunt at tip. 



Fig. 9. In a ripe flower insert the point of a pencil for instance, so as to rupture rostellum, and on withdrawing the pencil, 

 one or two pollinia will be found adhering to it. 



Pollinium, consisting of a club-shaped pollen-mass borne on a stalk, with a sticky gland at the base. 

 Fig 10. In a young unopened flower it is interesting to note that the Ovary is untwisted, and that the lip is uppermost (as 

 shown in Diagram). In expanding, however, the twisting of the ovary turns the parts of the flower right round, 

 and the lip comes to occupy its inferior position. 



The stalk-like ovary shows the flower to be sessile, and the Inflorescence is therefore a spike. 



Figs. 11 and 12. Transverse sections of Ovaries. t . . , 



The ovary is one-chambered, containing numerous ovules arranged along the walls in three principal rows. 



Fruit and Seed — 



Fig. 13. The Fruit has the remains of perianth adherent to it, and opens by three valves or lobes, leaving the ribs still stand- 

 ing between. 

 Fiff 14 Detach one of the Seeds from wall of fruit, and examine under microscope. 



*' ' The Seed consists of a Cover, which is irregularly netted, and an Embryo, which is a roundish undiffer- 



entiated mass of tissue. 



CLASSIFICATION. 



Class. — Monocotyledon. 

 Division. — Petaloidese. 

 Order. — Orch i dacesc. 



Perianth, irregular, superior. 



Androecium and Gynoscium, united. 



Pollen-grains in club-shaped masses. 



Ovary, inferior, one-chambered. 



Ovules, numerous; placentation, parietal. 



Fruit, capsular. 



Seed, without endosperm. 



