The youngest and largest plant family, comprising about seven hundred
and fifty genera and ten thousand species, highly specialized for
insect pollination, easily recognized as a whole, but many of its
members difficult to distinguish. Some tropical kinds are trees; ours
are usually herbs, sometimes shrubs, without stipules; the leaves
opposite, alternate or from the root; the flowers all small and crowded
in heads, on the enlarged top of the flower-stalk, which is called
the "receptacle," and surrounded by a common involucre of separate
bracts, few or many, arranged in one or more rows; the receptacle also
sometimes having scale-like or bristle-like bracts among the flowers,
its surface smooth, or variously pitted and honey-combed. The flowers
are sometimes perfect, or with only pistils, or only stamens, or with
stamens and pistils on different plants, or all kinds mixed. The
calyx-tube is sometimes a mere ring, or its margin consists of hairs,
bristles or scales, called the "pappus." The corollas are chiefly of
two sorts; they are tubular and usually have five lobes or teeth, but
often the flowers around the margin of the head are strap-shaped, that
is, the border of the corolla is expanded into what is called a "ray."
For instance, the yellow center, or "disk," of a Daisy is composed
of a crowded mass of tiny tube-shaped flowers, which is surrounded
by a circle of white, strap-shaped flowers, or rays, which look like
petals. A Thistle, on the other hand, has no rays and the head is
made up of tube-shaped flowers only. Stamens usually five, on the
corolla-tube, alternate with its lobes, anthers usually united into a
tube surrounding the style, which has two branches in fertile flowers,
but usually undivided in sterile flowers; ovary inferior, one-celled,
maturing into an akene, often tipped with hairs from the pappus to
waft it about, or with hooks or barbs to catch in fur of animals.
(Descriptions of genera have been omitted as too technical.)
There are many kinds of Carduus (Cnicus) (Cirsium), widely distributed;
with tubular flowers only.
[Sidenote: =Thistle=
_Càrduus Còulteri_
=Pink, crimson
Spring, summer
California=]
A strikingly handsome, branching plant, from three to seven feet high,
with light green leaves, very decorative in form, more or less downy
on the upper side and pale with down on the under. The flower-heads,
about two inches long, have bright lilac-pink or crimson flowers and
more or less woolly involucres. This grows in the hills and mountains
of the Coast Ranges.
[Illustration: Thistle--Carduus Coulteri.]
[Sidenote: =Arizona Thistle=
_Càrduus Arizònicus_
=Pink
Summer
Arizona=]
A very striking and decorative plant, both in form and color, from two
to six feet tall, with a pale, branching, leafy stem, covered with
close, white down, springing from a cluster of large root-leaves. The
leaves are gray-green, covered with white down, and show great beauty
of design, being sharply and symmetrically lobed and toothed, the
margins armed with long yellow prickles. The flower-heads are an inch
and a half long, with beautiful carmine and pale-pink flowers, all with
no tinge of purple, the vivid spots of color giving a very brilliant
effect in contrast with the pale foliage. This grows in the Grand
Canyon and is conspicuous along the Berry trail, a little way below the
rim.
[Sidenote: =Thistle=
_Càrduus candadíssimus_
=Pink, crimson
Summer
California=]
A very handsome and decorative plant, about three feet tall, with
spreading stems, covered with white down, and dull-green leaves, pale
with down on the under side and often covered with white down all over.
The handsome flower-heads are two inches or more long and have deep
pink or crimson flowers and very woolly involucres.
[Sidenote: =California Thistle=
_Càrduus Califórnicus_
=White
Spring
California=]
A branching plant, from two to six feet tall, very leafy below,
with very dark bluish-green leaves, with more or less woolly down
on the upper side and pale with matted down on the under side. The
flower-heads are nearly three inches across, with cream-white or rarely
purple flowers, and the bracts are caught together with silky, cobwebby
down. This is common in the Sierra Nevada.
[Sidenote: =Western Thistle=
_Càrduus occidentàlis_
=Red, purple
Spring
Cal., Oreg.=]
A stout plant, two or three feet high, with large prickly leaves, and
more or less covered all over with cottony wool. The flower-head is
about two inches long, and nearly as wide, and is a ball of white,
cobwebby wool, pierced all over with brown spines, and tipped with
wine-colored flowers. This is common on sandy hills, near the coast,
from San Francisco south. Yellow-spined Thistle, _C. ochrocéntrus_,
found in Nevada and Arizona and as far east as Colorado, has purple
flowers and leaves deeply slashed and armed with long yellow spines.
This grows at the Grand Canyon.
[Illustration: Arizona Thistle--Carduus Arizonicus.]
[Illustration: Thistles.
Carduus Californicus.