. The Indiana weed book. Weeds. THE FLOWERS OF WEEDS. 35 subdivided, as in the dissected leaves of yarrow, dog-fennel, etc. The tip of a leaf may be acute or pointed, acuminate or longer pointed, obtuse or dull, emarginaie or notched, etc. Both leaves and stems may be clothed with hairs, as in the corn cockle, or glabrous, without hairs. The hairs, when present, differ greatly in length, stiffness, abundance, etc., in the various weeds. The leaves of many weeds bear on the stalk near the base a pair of leaf-like expansions called stipules (Fig. 15, d), which are usually green but often colorle
. The Indiana weed book. Weeds. THE FLOWERS OF WEEDS. 35 subdivided, as in the dissected leaves of yarrow, dog-fennel, etc. The tip of a leaf may be acute or pointed, acuminate or longer pointed, obtuse or dull, emarginaie or notched, etc. Both leaves and stems may be clothed with hairs, as in the corn cockle, or glabrous, without hairs. The hairs, when present, differ greatly in length, stiffness, abundance, etc., in the various weeds. The leaves of many weeds bear on the stalk near the base a pair of leaf-like expansions called stipules (Fig. 15, d), which are usually green but often colorless. The margins of sessile leaves may sometimes extend down along the stem as in mullen. Such leaves are said to be decurrcnt and the stem winged. Bracts, scales, glumes, are only leaves reduced in size which are mainly used to protect the flowers. The seed leaves or cotyledons, are small. Fig. 9. Illustrating the parts of a flower: a, flower of poppy showing the 4 sets cf floral organs, viz., k, the sepals, together called the calyx; c, the petals, together called the corolla; a, the numerous stamens; g, the 2 pis- ii'.s which contain the ovules. 6, Flower of cinquefoil showing 3 broad sepals, 2 smaller petals alternating with them, a group of stamens, and a large receptacle bearing numerous small pistils, c, Butterfly-shaped flower of sweet pea; d, same spread to show the parts; s, the standard, w, the wings, k, the keel, (After Strasburger and Gray.) leaves which exist in all seeds. In some plants, as the squash and beech-nut, they arise above the ground when the seed sprouts. Endogens have but one seed leaf while all exogens have two. The flowers of a weed.—The flower is that part of a plant whose chief duty it is to produce seeds or the young of future plants. A complete flower consists of the floral envelope, (Fig. 9,. a), or calyx and corolla, and the essential or sexual organs, the stamens and pistils. If any one of these four divisions of a flower is absent it
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectweeds, bookyear1912
