A large family, widely distributed. Both the English and Latin names
are appropriate, for the watery juice of these plants is pungent, like
mustard, and the flowers spread out their four petals in the form of a
cross. They are herbs, the leaves alternate or from the root, usually
with no leaf-stalks. The flowers have four petals, with claws; four
sepals, the two outer ones narrow, apt to drop off; six stamens, two
of them short. The ovary is superior, usually with a single style
and stigma, and usually develops into a pod, divided in two by a
transparent partition, which remains after the pod has opened from
below; in some kinds the pod remains closed. The flowers generally grow
in clusters and though they are often small they produce honey and so
are frequented by bees and flies. The family is easily recognized by
the four petals and in most species by two stamens being shorter than
the others, but the flowers are so much alike that the various kinds
have to be determined by examining the fruit. Radish and Horse-radish,
Mustard and Water-cress all belong to this family, as well as many
familiar garden flowers, such as Sweet Alyssum, Candytuft, Rockets, and
Stocks, and many are common weeds, such as Peppergrass and Shepherd's
Purse.
There are several kinds of Dentaria, smooth perennials, with rather
large white or pink flowers and tuberous rootstocks.
[Sidenote: =Milk Maids, Pepper-root=
_Dentària Califórnica_
=White, pink
Spring
Cal., Oreg.=]
A charming plant, with a purplish stem, from six inches to two feet
tall, and pretty leaves, varying in shape, those from the root being
roundish in outline, or with three leaflets, but the stem-leaves with
three or five leaflets. The flowers are about three-quarters of an
inch across, with pure-white or pale-pink petals. This is one of the
loveliest of the early spring flowers in the Coast Ranges and usually
found in damp spots, both in woods and open places, often whitening the
meadows with its blossoms.
[Illustration: Milk Maids--Dentaria Californica.]
There are a good many kinds of Thelypodium, natives of North America,
all western or southwestern; mostly smooth plants, the leaves usually
with leaf-stalks, the flowers in clusters; stamens long, conspicuous,
with very narrow, arrow-shaped anthers; pods long, cylindrical or
four-sided, often twisted, sometimes on a slender stalk; seeds oblong,
flattish, in one row in each cell.
[Sidenote: _Thelypòdium torulòsum_
=Lilac
Spring, summer
West, etc.=]
This has small flowers, but often grows in such quantities on the flats
near Salt Lake that it tints the fields with purple. The purplish
stem is from twelve to fifteen inches tall and the leaves are light
bluish-green and very smooth, the root-leaves with long leaf-stalks,
and the stem-leaves arrow-shaped and clasping at base. The flowers
are about half an inch across, with a purplish-tinged calyx and pale
pinkish-lilac petals, and form flat-topped clusters. The pods are
spreading and rather knobby. This usually grows on dry hills, reaching
an altitude of over nine thousand feet, as far east as Wyoming.
There are many kinds of Arabis, widely distributed, with small, white
or purplish flowers.
[Sidenote: =Fendler's Arabis=
_Árabis Féndleri_
=Magenta
Spring
Arizona=]
This is a rather pretty plant, a foot or more tall, with more or less
hairy stems and leaves and pretty clusters of magenta flowers, each
about a quarter of an inch across. It grows on the rim of the Grand
Canyon.
There are many kinds of Erysimum, most abundant in Europe and Asia.
They are usually biennial or perennial, more or less downy; mostly with
yellow flowers; the pods long, narrow and squarish or flattish, rarely
round, with numerous seeds, in one row. In Europe these plants often
grow in the crannies of old walls, hence the common name.
[Sidenote: =Western Wallflower=
_Erýsimum ásperum_
=Orange, lemon-yellow
Spring, summer
West, etc.=]
The vivid glowing orange of these handsome flowers is exceedingly
effective among the dark tree-trunks of the mountain forests where they
often grow. They are widely distributed as far east as Ohio. The stout,
purplish stems are from one to two feet tall and the long, narrow
leaves, often toothed, are apt to be purplish on the under side, and
both stem and leaves are rather rough. The fragrant flowers, each
about three-quarters of an inch across, form a handsome cluster, about
three inches across. The calyx is yellow, the pistil green, and the
anthers brown. The conspicuous, four-sided pods are spreading or erect,
from one to five inches long, with a stout beak. In the high mountains
the orange-color gives way to the variety _perénne_, with lemon-colored
flowers, perhaps commoner than the orange, not so tall, and wonderfully
handsome in the Wasatch Mountains, around Mt. Rainier and similar
places, and widely distributed. The Cream-colored Wallflower, _E.
capitàtum_, blooms early, growing near the coast; the flowers large,
handsome, but not sweet-scented.
[Illustration: Western Wall-flower--Erysimum asperum.]
[Illustration: Thelypodium torulosum.