Part 21 (1/2)
Flowering Season - July-August.
Distribution - From British Columbia to the Atlantic; eastern half of the United States southward to the Carolinas.
Wonderfully interesting structure and the comparative rarity of this orchid, rather than superficial beauty, are responsible for the thrill of pleasure one experiences at the sight of the spike of unpretentious flowers. Two great leaves, sometimes as large as dinner plates, attract the eye to where they glisten on the ground. The spur of the blossom, the nectary, ”implies a welcome to a tongue two inches long, and will reward none other,” says William Hamilton Gibson. ”This clearly shuts out the bees, b.u.t.terflies, and smaller moths. What insect, then, is here implied? The sphinx moth, one of the lesser of the group. A larger individual might sip the nectar, it is true, but its longer tongue would reach the base of the tube without effecting the slightest contact with the pollen, which is, of course, the desideratum.” How the moth, in sipping the nectar, thrusts his head against the sticky b.u.t.tons to which the pollen messes are attached, and, in trying to release himself, loosens them; how he flies off with these little clubs sticking to his eyes; how they automatically adjust themselves to the att.i.tude where they will come in contact with the stigma of the next flower visited, and so cross-fertilize it, has been told in the account of the great purple-fringed orchis of similar construction. To that species the interested reader is, therefore, referred; or, better still, to the luminous description by Dr. Asa Gray.
WHITE-FRINGED ORCHIS (Habenaria blephariglottis) Orchid family
Flowers - Pure white, fragrant, borne on a spike from 3 to 6 in.
long. Spur long, slender; oval sepals; smaller petals toothed; the oblong lip deeply fringed. Stem: Slender, 1 to 2 ft. high.
Leaves: Lance-shaped, parallel-veined, clasping the stem; upper ones smallest.
Preferred Habitat - Peat-bogs and swamps.
Flowering Season - July-August.
Distribution - Northeastern United States and eastern Canada to Newfoundland.
One who selfishly imagines that all the floral beauty of the earth was created for man's sole delight will wonder why a flower so exquisitely beautiful as this dainty little orchid should be hidden in inaccessible peat-bogs, where overshoes and tempers get lost with deplorable frequency, and the water-snake and bittern mock at man's intrusion of their realm by the ease with which they move away from him. Not for man, but for the bee, the moth, and the b.u.t.terfly, are orchids where they are and what they are.
The white-fringed orchis grows in watery places that it may more easily manufacture nectar, and protect itself from crawling pilferers; its flowers are cl.u.s.tered on a spike, their lips are fringed, they have been given fragrance and a snowy-white color that they may effectually advertise their sweets on whose removal by an insect benefactor that will carry pollen from flower to flower as he feeds depends their chance of producing fertile seed. It is probable the flower is white that night-flying moths may see it s.h.i.+ne in the gloaming. From the length and slenderness of its spur it is doubtless adapted to the sphinx moth.
At the entrance to the nectary, two sticky disks stand on guard, ready to fasten themselves to the eyes of the first moth that inserts his tongue; and he finds on withdrawing his head that two pollen-ma.s.ses attached to these disks have been removed with them. This plastering over of insects' eyes by the orchids might be serious business, indeed, were not the lepidoptera gifted with numerous pairs. The fragrance of many orchids, however, would be a sufficient guide even to a blind insect. With the pollen-ma.s.ses sticking to his forehead, the moth enters another flower and necessarily rubs off some grains from the pollen ma.s.ses, that have changed their att.i.tude during his flight that they may be in the precise position to fertilize the viscid stigma. In almost the same way the similar Yellow-Fringed Orchis (H. ciliaris) and the great green orchids compel insects to work for them.
A larger-flowered species, the PRAIRIE WHITE-FRINGED ORCHIS (H.
lepicophea), found in bloom in June and July, on moist, open ground from western New York to Minnesota and Arkansas, differs from the preceding chiefly in having larger and greenish-white flowers, the lip cleft into wedge-shaped segments deeply fringed.
The hawk-moth removes on its tongue one, but not often both, of the pollinia attached to disks on either side of the entrance to the spur.
NODDING LADIES' TRESSES or TRACES (Gyrostachys cernua; Spiranthes cernua of Gray) Orchid family
Flowers - Small, white or yellowish, without a spur, fragrant, nodding or spreading in 3 rows on a cylindrical, slightly twisted spike 4 or 5 in. long. Side sepals free, the upper ones arching, and united with petals; the oblong, spreading lip crinkle-edged, and bearing minute, hairy callosities at bases Stem: 6 in. to 2 ft. tall, with several pointed, wrapping bracts. Leaves: From or near the base, linear, almost gra.s.s-like.
Preferred Habitat - Low meadows, ditches, and swamps.
Flowering Season - July-October.
Distribution - Nova Scotia to the Gulf of Mexico, and westward to the Mississippi.
This last orchid of the season, and perhaps the commonest of its interesting tribe in the eastern United States, at least, bears flowers that, however insignificant in size, are marvelous pieces of mechanism, to which such men as Charles Darwin and Asa Gray have devoted hours of study and, these two men particularly, much correspondence.
Just as a woodp.e.c.k.e.r begins at the bottom of a tree and taps his way upward, so a bee begins at the lower and older flowers on a spike and works up to the younger ones; a fact on which this little orchid, like many another plant that arranges its b1ossoms in long racemes, depends. Let us not note for the present what happens in the older flowers, but begin our observations, with the help of a powerful lens, when the bee has alighted on the spreading lip of a newly opened blossom toward the top of the spire. As nectar is already secreted for her in its receptacle, she thrusts her tongue through the channel provided to guide it aright, and by the slight contact with the furrowed rostellum, it splits, and releases a boat-shaped disk standing vertically on its stern in the pa.s.sage. Within the boat is an extremely sticky cement that hardens almost instantly on exposure to the air. The splitting of the rostellum, curiously enough, never happens without insect aid; but if a bristle or needle be pa.s.sed over it ever so lightly, a stream of sticky, milky fluid exudes, hardens, and the boat-shaped disk, with pollen ma.s.ses attached, may be withdrawn on the bristle just as the bee removes them with her tongue. Each pollinium consists of two leaves of pollen united for about half their length in the middle with elastic threads.
As the pollinia are attached parallel to the disk, they stick parallel on the bee's tongue, yet she may fold up her proboscis under her head, if she choose, without inconvenience from the pollen ma.s.ses, or without danger of loosening them. Now, having finished sucking the newly opened flowers at the top of the spike, away she flies to an older flower at the bottom of another one. Here a marvelous thing has happened. The pa.s.sage which, when the flower first expanded, scarcely permitted a bristle to pa.s.s, has now widened through the automatic downward movement of the column in order to expose the stigmatic surfaces to contact with the pollen ma.s.ses brought by the bee. Without the bee's help this orchid, with a host of other flowers, must disappear from the face of the earth. So very many species which have lost the power to fertilize themselves now depend absolutely on these little pollen carriers, it is safe to say that, should the bees perish, one half our flora would be exterminated with them. On the slight downward movement of the column in the ladies' tresses, then, as well as on the bee's ministrations, the fertilization of the flower absolutely depends. ”If the stigma of the lowest flower has already been fully fertilized,” says Darwin, ”little or no pollen will be left on its dried surface; but on the next succeeding flower, of which the stigma is adhesive, large sheets of pollen will be left. Then as soon as the bee arrives near the summit of the spike she will withdraw fresh pollinia, will fly to the lower flowers on another plant, and fertilize them; and thus, as she goes her rounds and adds to her store of honey, she continually fertilizes fresh flowers and perpetuates the race of autumnal spiranthes, which will yield honey to future generations of bees.”
The SLENDER LADIES' TRESSES (G. gracilis; [S. gracilis]), with a range and season of blossom similar to the preceding species, and with even smaller white, fragrant flowers, growing on one side of a twisted spike, chooses dry fields, hillsides, open woods, and sandy places - queer habitats for a member of its moisture-loving tribe. Its leaves have usually fallen by flowering time. The cl.u.s.ter of tuberous, spindle-shaped roots are an aid to identification.
LESSER RATTLESNAKE PLANTAIN [DWARF RATTLESNAKE-PLANTAIN]
(Peramium repens; Goodyera repens of Gray) Orchid family
Flowers - Small, greenish white, the lip pocket-shaped, borne on one side of a bracted spike 5 to 10 in. high, from a fleshy, thick fibrous root. Leaves: From the base, tufted, or ascending the stem on one side for a few inches, 1/2 in. to over 1 in.
long, ovate, the silvery-white veins forming a network, or leaf blotched with white.
Preferred Habitat - Woods, especially under evergreens.
Flowering Season - July-August.
Distribution - Colorado eastward to the Atlantic, from Nova Scotia to Florida. Europe and Asia.
Tufts of these beautifully marked little leaves carpeting the ground in the shadow of the hemlocks attract the eye, rather than the spires of insignificantly small flowers. Whoever wishes to know how the b.u.mblebee ruptures the sensitive membrane within the tiny blossom with her tongue, and draws out the pollinia that are instantly cemented to it after much the same plan employed by the ladies' tresses, must use a good lens in studying the operation.