In describing the common milkweed (q.v.), so many statements were made that apply quite as truly to this far daintier and more ethereal species, the reader is referred back to the pink and magenta section.Compared with some of its rank-growing, heavy relatives, how exquisite is this little denizen of the uplands, with its whorls of needle-like leaves set at intervals along a slender swaying stem! The entire plant, with its delicate foliage and greenish-white umbels of flowers, rather suggests a member of the carrot tribe; and much the same class of small-sized, short-tongued visitors come to seek its accessible nectar as we find about the parsnips, for example.When little bees alight -and these are the truest benefactors, however frequently larger bees, wasps, flies, and even the almost useless butterflies come around - their feet slip about within the low crown to find a secure lodging.As they rise to fly away after sucking, the pollen masses which have attached themselves to the hairs on the lower part of their legs are drawn out, to be transferred to other blossoms, perhaps today, perhaps not for a fortnight.
Annoying as they may be, it is very rarely, indeed, that an insect can rid itself of the pollen masses carried from either orchids or milkweeds, except by the method Nature intended; and it is not until the long-suffering bee is outrageously loaded that he attains his greatest usefulness to milkweed blossoms."Of ninety-two specimens bearing corpuscula of Asclepias verticillata," says Professor Robertson, "eighty-eight have them on hairs alone, and four on the hairs and claws." And again: "As far as the mere application of pollen to an insect is concerned, a flower with loose pollen has the advantage.But the advantage is on the side of Asclepias after the insect is loaded with it.
It is only a general rule that insects keep to flowers of a particular species on their honey and pollen gathering expeditions.If a bee dusted with loose pollen visits flowers of another species, it will not long retain pollen in sufficient quantity to effectually fertilize flowers of the original species.On the other hand, if an insect returns at any time during the day, or even after a few days, to the species of Asclepias from which it got a load of pollinia, it may bring with it all or most of the pollinia which it has carried from the first plants visited.The firmness with which the pollinia keep their hold on the insect is one of the best adaptations for cross-fertilization."Ants, the worst pilferers of nectar extant, find the hairy stem of the whorled milkweed, as well as its sticky juice, most discouraging, if not fatal, obstacles to climbing.How daintily the goldfinch picks at the milkweed pods and sets adrift the seeds attached to silky aeronautic fluff!
WILD POTATO-VINE; MAN-OF-THE-EARTH; MECHA-MECK(Ipomoea pandurata) Morning-glory family Flowers - Funnel form, wide-spread, 2 to 3 in.long, pure white or pinkish purple inside the throat; the peduncles 1 to 5flowered.Stem: Trailing over the ground or weakly twining, 2 to 12 ft.long.Leaves: Heart, fiddle, or halbert shaped (rarely 3-lobed), on slender petioles.Root: Enormous, fleshy.
Preferred Habitat - Dry soil, sandy or gravelly fields or hills.
Flowering Season - May-September.
Distribution - Ontario, Michigan, and Texas, east to the Atlantic Ocean.
No one need be told that this flaring, trumpet-shaped flower is next of kin to the morning-glory that clambers over the trellises of countless kitchen porches, and escapes back to Nature's garden whenever it can.When the ancestors of these blossoms welded their five petals into a solid deep bell, which still shows on its edges the trace of five once separate parts, they did much to protect their precious contents from rain; but some additional protection was surely needed against the little interlopers not adapted to fertilize the flower, which could so easily crawl down its tube.Doubtless the hairs on the base of the filaments, between which certain bumblebees and other long-tongued benefactors can easily penetrate to suck the nectar secreted in a fleshy disk below, act as a stockade to little would-be pilferers.The color in the throat serves as a pathfinder to the deep-hidden sweets.How pleasant the way is made for such insects as a flower must needs encourage! For these the perennial wild potato vine keeps open house far later in the day than its annual relatives.Professor Robertson says it is dependent mainly upon two bees, Entechnia taurea and Xenoglossa ipomoeae, the latter its namesake.
One has to dig deep to find the huge, fleshy, potato-like root from which the vine derived its name of man-of-the-earth.Such a storehouse of juices is surely necessary in the dry soil where the wild potato lives.
Happily, the COMMON MORNING-GLORY (I.purpurea) - the Convolvulus major of seedsmen's catalogues - has so commonly escaped from cultivation in the eastern half of the United States and Canada as now to deserve counting among our wild flowers, albeit South America is its true home.Surely no description of this commonest of all garden climbers is needed; everyone has an opportunity to watch how the bees cross-fertilize it.
