Part 23

=Marsh Orchis= (Orchis latifolia).

There are nearly forty British species of Orchideæ, divided into sixteen genera; and in the space at our disposal it is impossible to give anything like an adequate account of the group or of the specific characters. An attempt will be made, however, to make the reader acquainted with the general structure by means of three figures. The first of these represents the Marsh Orchis (O. latifolia), a species commonly to be met in wet meadows and marshy places, flowering from May to July. The two tubers are palmate, that is, more or less flattened like a hand, and terminating in finger-like processes. The leaves chiefly spring from the summit of one of these tubers, the lowest acting as sheath for the next, and so on, the tubular flower-stem rising through all the sheaths. The leaves are oblong, and spotted with purple. The inflorescence is a spike, the flowers crowded upon it, but separated by the long three-nerved green bracts. The structure of these flowers will be found to differ widely from all we have considered in these pages. The perianth is placed above the (consequently inferior) ovary, which is twisted. This twist, it will be well to bear in mind, brings the flower “upside down.” The three sepals and the three petals are equally coloured, and it is therefore convenient to speak of them as the perianth. There is only one stamen, which is supported by the pistil. Two of the perianth leaves combine to form a hood over the stamen, and a third is greatly larger than the others, divided into three lobes and hanging down like the lip of a labiate flower. This is known as the labellum, and it is continued backwards and downwards as a hollow spur, in which, however, honey is not secreted. At the top of this spur, at the back, is the stigmatic surface, and above it protrudes a fleshy knob, called the rostellum, which supports the anther. This organ consists of two lobes, side by side, which open in front, and reveal in each a mass of pollen grains tied together by elastic threads and attached to a slender foot-stalk with a sticky base. This is a tedious description, though we have made it as brief as possible. The reader shall see the reason for it if he will conduct a little experiment. We may premise that these orchids are fertilized by long-tongued insects, who suck the juice through the tender skin lining the spur.

Now for the experiment. Take a finely-pointed pencil, which we will pretend is the head and tongue of a humble-bee in search of this sweet juice. We push the point gently down the spur, when a part of the pencil touches against the rostellum and presses it down, touches lightly the viscid feet of the pollen masses (pollinia), and as the pencil is withdrawn both come with it, and stick out from it like a pair of horns. Be careful to hold the pencil in the exact position it now occupies, and watch. The heavy heads of the pollinia are drooping forward, but after a few minutes they cease to fall lower. Now push the pencil into this other flower. The pollen-masses go directly to the stigma, and some of the pollen is detached. If you are watching where orchids grow it is no uncommon thing to see insects flying around with these pollinia attached to their heads or tongues like a pair of horns.

It will be seen to be impossible for the pollen to fall upon the stigma of the same flower, and from its elastic attachments it is impossible that it should be carried by the wind to another flower, so that insect agency is here an absolute necessity.

Orchis latifolia.

--ORCHIDACEÆ.--]

Habenaria bifolia.

--ORCHIDEÆ.--]

=The Butterfly Orchis= (Habenaria bifolia).

This species is very similar in structure and habit to the Marsh Orchis, but the tubers are more cylindrical in shape, the radical leaves almost always restricted to two, the flower-spike lax. Flowers white with a greenish tinge, the labellum and spur very long: fragrant. The stigma two-lobed. Fertilized by moths. Occurs in meadows, hill-sides and woods, flowering from June to August.

=The Bee Orchis= (Ophrys apifera).

In the genus Ophrys we have three species whose flowers bear quite startling likeness to a bee, spider and fly respectively. What is the purpose of this counterfeit presentment it is difficult to conjecture. It has been suggested that it might be to warn off or deceive insects, as the flowers are self-fertilized, but Charles Darwin did not think this was the probable reason. There is no spur in this group, there is no rostellum, and the ovary is not twisted. The stalks (caudicles) of the pollinia are so long and thin that the weight of the pollen masses causes them to bend over and touch against the stigma, fertilizing it.

I. Bee Orchis (O. apifera). The labellum is very convex and broad, three-lobed, of a rich velvety-brown colour, with a tail. The sepals are pinkish. The spike has only about half a dozen flowers upon it, with a large leafy bract under each. Hillsides, fields and copses on chalk and limestone, chiefly in the South of England and Ireland. June and July. (Plate 77.)

II. Spider Orchis (O. aranifera). Similar to the last, but the sepals greenish, labellum differently marked, and without a tail. Similar situations to apifera, but much more rare. April and May.

III. Fly Orchis (O. muscifera). Sepals greenish, labellum narrow, flat, brown, with a yellow-edged, squarish blue patch. Strikingly like a fly. May to July.

The name of the genus is from the Greek, ophrus, an eyebrow, said to refer to the markings on the labellum.

Several other British species in different genera from those named bear similarly strange likenesses, such as the extremely rare Lizard Orchis (Orchis hircina), but some of the foreign forms are more remarkable still.

In addition to the species figured and those briefly described, we would call attention to a few others that may come under the rambler’s notice. In boggy ground and sphagnum beds he may be so fortunate as to find the rare Bog Orchis (Malaxis paludosa), a small plant with tiny yellow-green flowers (July to September), and the scanty leaves producing bulbils from their edges which grow into new plants. In similar situations in the eastern counties he may even find the larger but much rarer Fen Orchis (Liparis loeselii).

A singular species, to be found chiefly in beechwoods throughout the country, is the Birds’-nest Orchis (Neottia nidus-avis), so called from the peculiar character of its roots, which are stout and juicy, and woven into a resemblance to a nest. The whole plant is of a pretty uniform brown tint--both stem and flowers. There are no leaves, for the plant lives upon decaying vegetable matter, and has no necessity to bother about chlorophyll. It is botanically known as a saprophyte. Flowers June and July.

The very distinct Twayblade (Listera ovata) is sure to be encountered in woods and pastures. Its two leaves are very broad, and appear to be opposite, but are not really so. The flowers are small and greenish; they appear in May. There is a singular fact in connection with the fertilization of this plant that should be noted. The pollen-masses are dry and friable, and would not be likely to adhere to insects. But if the rostellum be touched ever so lightly, it instantly exudes a gummy fluid, which enables the pollen to stick tightly to the insect causing the irritation. Examine the flower with your lens, irritate the rostellum by prodding it with the point of a hair from your own head, and note what you observe.

At the end of Summer in dry pastures there may be found a slender plant with a twisted spike of fragrant white flowers. These flowers are very small, enclosed each in a hood-like bract. It is the Autumnal Lady’s-tresses (Spiranthes autumnalis). The rosette of leaves from the root does not appear until after the flowers.

Ophrys apifera.

--ORCHIDEÆ.--]

Campanula rotundifolia.

--CAMPANULACEÆ.--

=Common Centaury.=

Erythræa centaurium.

--GENTIANEÆ.--]