The Yellow Flag.
Nearly all the species have very narrow leaves, with prominent stipules at the base; and their flowers grow in erect or horizontal catkins with undivided scales. The flowers are always unisexual, the male and female blossoms being produced on separate trees. The former have from two to five stamens; and the latter a one-celled ovary that ripens to a capsule containing many seeds, each with a tuft of silky hairs. A few of these trees are common in marshes and bogs, but they are so similar in their general features that the identification of species is somewhat difficult for a beginner.
Some of our marshes and boggy pools are beautifully decorated from May to July by the large, bright flowers of the Yellow Iris or Flag (Iris Pseudacorus), which belongs to the order Iridaceæ. This plant has a thick rhizome which creeps horizontally below the ground, and a round stem from one to three feet high. Two or three flowers grow on the stem, each with a sheathing bract at the base of its stalk. The perianth consists of six segments, the outer three broadly ovate at the top, and spreading; and the inner three narrower, shorter, and erect. There are three stamens; and an inferior ovary with three large petal-like stigmas, longer than the inner segments of the perianth, divided into two at the tip. The fruit is a large capsule, two or three inches long, containing many brownish-yellow seeds.
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WOODS AND THICKETS IN SUMMER
A large number of the flowers that grow in woods bloom early in the spring, before the buds of the trees have expanded, or, at least, before the foliage is sufficiently dense to cover the ground with its shadow. Some, however, are not so dependent on the direct rays of the sun, but thrive even better in the shaded, moist atmosphere of wooded ground. Others there are which seem grateful for the warm rays of the summer sun, but grow to their greatest luxuriance in the moist and partially-shaded ground of underwood and thicket, trusting to the rigidity of their own erect stems, or to the climbing habit which they have acquired, to bring their leaves and blossoms in full view of the sun during some part of the day.
Plants such as these are selected for description in this chapter; and although we may speak of their flowers as the summer blossoms of woods, thickets and copses, we must be prepared to meet with several of them outside these habitats, particularly in damp places that are more or less protected from the heat of the sun.
Our first in this series is the Lime Tree (Tilia europæa) of the order Tiliaceæ, which grows wild in many of our woods, but has been planted to such an extent that it may be found in almost every cultivated district except in the extreme North. Its leaves are stalked, alternate, heart-shaped or broadly ovate, very pointed, serrate, smooth above, and slightly downy below. The flowers, which appear during June and July, are of a pale yellowish green colour, and are arranged in cymes, on axillary, drooping peduncles that are attached for nearly half their length to a long, leafy bract. There are five sepals, which fall early; five petals; and many stamens that are united at their bases into clusters. The blossoms have a very sweet scent, and produce such an abundance of nectar that they are very attractive to bees and other insects. The fruit is a woody nut, globular or more or less angled, five-celled, with two seeds in each cell.