This section is from the book "Nature's Garden", by Neltje Blanchan. Also available from Amazon: Nature's Garden; An Aid To Knowledge Of Our Wild Flowers And Their Insect Visitors.
Flowers - Bright yellow, fading pale, 1/4 to 1/2 in. across, 4-parted, in elongated racemes; quickly followed by narrow upright 4-sided pods about 1/2. in. long appressed against the stem. Stem: Erect, 2 to 7 ft. tall, branching. Leaves: Variously lobed and divided, finely toothed, the terminal lobe larger than the 2 to 4 side ones.
Flowering Season - June - November.
Distribution - Common throughout our area; naturalized from Europe and Asia.
" The kingdom of heaven is like unto a grain of mustard seed, which a man took and sowed in his field: which indeed is less than all seeds; but when it is grown, it is greater than the herbs, and becometh a tree, so that the birds of the air come and lodge in the branches thereof."
Commentators differ as to which is the mustard of the parable - this common black mustard, or a rarer shrub-like tree (Salvadora Persica), with an equivalent Arabic name, a pungent odor, and a very small seed. Inasmuch as the mustard which is systematically planted for fodder by Old World farmers grows with the greatest luxuriance in Palestine, and the comparison between the size of its seed and the plant's great height was already proverbial in the East when Jesus used it, evidence strongly favors this wayside weed. Indeed, the late Dr. Royle, who endeavored to prove that it was the shrub that was referred to, finally found that it does not grow in Galilee.
Now, there are two species which furnish the most powerfully pungent condiment known to commerce; but the tiny dark brown seeds of the black mustard are sharper than the serpent's tooth, whereas the pale brown seeds of the White Mustard, often mixed with them, are far more mild. The latter (Sinapis alba) is a similar, but more hairy, plant, with slightly larger yellow flowers. Its pods are constricted like a necklace between the seeds.
The coarse Hedge Mustard (Sisymbrium officinale), with rigid, spreading branches, and spikes of tiny pale yellow flowers, quickly followed by awl-shaped pods that are closely appressed to the stem, abounds in waste places throughout our area. It blooms from May to November, like the next species.
Another common and most troublesome weed from Europe is the Field or Corn Mustard, Charlock or Field Kale (Brassica arvensis) - Sinapis arvensis of Gray - found in grain fields, gardens, rich waste lands, and rubbish heaps. The alternate leaves, which stand boldly out from the stem, are oval, coarsely saw-toothed, or the lower ones more irregular, and lobed at their bases, all rough to the touch, and conspicuously veined. The four-parted yellow flowers, measuring half an inch or more across, have six stamens (like the other members of this cross-bearing family), containing nectar at their bases. Two of them are shorter than the other four. Honey-bees, ever abundant, the brilliant Syrphidae flies which love yellow, and other small visitors after pollen and nectar, to obtain the latter insert their tongues between the stamens, and usually cross-fertilize the flowers. In stormy weather, when few insects fly, the anthers finally turn their pollen-covered tips upward; then, by a curvature of the tip of the stamens, they are brought in contact with the flower's own stigma; for it is obviously better that even self-fertilized seed should be set than none at all. (See Ladies'-smock, p. 189.) "The birds of the air" may not lodge in the charlock's few and feeble branches; nevertheless they come seeking the mild seeds in the strongly nerved, smooth pods that spread in a loose raceme. Domestic pigeons eat the seeds greedily.
The highly intelligent honey-bee, which usually confines itself to one species of plant on its flights, apparently does not know the difference between the field mustard and the Wild Radish, or Jointed or White Charlock (Raphanus Raphanistrum); or, knowing it, does not care to make distinctions, for it may be seen visiting these similar flowers indiscriminately. At first the blossoms of the radish are yellow, but they quickly fade to white, and their purplish veins become more conspicuous. Rarely the flowers are all purplish. The entire plant is rough to the touch; the leaves, similar to those of the garden radish, are deeply cleft (lyrate-pinnatifid); the seed pods, which soon follow the flowers up the spike, are nearly cylindric when fresh, but become constricted between the seeds, as they dry, until each little pod looks like a section of a bead necklace.
The Garden Radish of the market (R. sativus), occasionally escaped from cultivation, although credited to China, is entirely unknown in its native state. "It has long been held in high esteem," wrote Peter Henderson, "and before the Christian era a volume was written on this plant alone. The ancient Greeks, in offering their oblations to Apollo, presented turnips in lead, beets in silver, and radishes in vessels of beaten gold." Pliny describes a radish eaten in Rome as being so transparent one might see through the root. It was not until the sixteenth century that the plant was introduced into England. Gerarde mentions cultivating four varieties for Queen Elizabeth in Lord Burleigh's garden.
The Yellow Rocket, Herb of St. Barbara, Yellow Bitter-cress, Winter- or Rocket-cress (Barbarea Barbarea) - B. vulgaris of Gray - sends up spikes of little flowers like a yellow sweet alys-sum as early as April, and continues in bloom through June. Smooth pods about one inch long quickly follow. The thickish, shining, tufted leaves, very like the familiar water-cress (Roripa Nasturtium), were formerly even more commonly eaten as a salad. In rich but dry soil the plant flourishes from Virginia far northward, locally in the interior of the United States and on the Pacific Coast.