The central or disc flowers are tubular. Which disc flowers open first, those near the middle or those nearer the edge of the disc? Pick off a flower and notice the 5-toothed corolla. Tear the corolla down with a needle, and observe the tiny stamens (5) fixed on the [Pg 112] corolla-tube. The anthers are joined together. Notice the divided stigma of the pistil. The white and pink ray flowers have strap-shaped corollas. They have no stamens, but each has a pistil like that of a disc flower. What do you think is the object of the ray flowers being so conspicuous? Why do they close over the disc at night? Notice the large number of green bracts below the disc. 2. The dandelion.—Compare the dandelion (Fig. 85). Notice that all the flowers are strap-shaped, like the ray flowers of the daisy. Pull one out, and make out the strap-like corolla, the five stamens with joined anthers, and the double stigma (Fig. 86, 2). Notice the tuft of fine hairs below the corolla and above the knob-like ovary. The tuft of hairs is the top of the calyx-tube. When the flowers have been fertilised, the yellow corollas wither, and each calyx-tube elongates until it is about an inch long, the tuft of fine hairs being still at the top (4). Blow a “clock,” and notice how easily the fruits are detached from the disc and how slowly they settle. What advantage is this to the plant? Fig. 85.—Dandelion. (× ¼.) 3. The thistle.—Compare the thistle (Fig. 87). The bracts are very prickly. Is this an advantage? Are the flowers tubular or strap-shaped? Examine the fruits (“thistle down”) and compare with those of dandelion. The daisy.—What is generally called the “flower” of the daisy (Fig. 84) really consists of a very large number of small separate [Pg 113] flowers set close together on a flattened disc or receptacle. The group of flowers is called a head. On the lower surface of the head are several green leaves, or bracts, which protect the bud before it opens. The flowers of a daisy-head are of two kinds. The white or pink straps set round the edge of the head are the corollas of the ray flowers. They have no stamens, but a pistil with a divided stigma is present in each. The disc flowers are yellow and tubular. The corolla consists of five united petals. On it are fixed five stamens, the anthers of which are joined together. The pistil is like that of a ray flower. No calyx is present in either the ray or disc flowers of the daisy. The daisy is fertilised by the aid of insects which are attracted by the strap-like corollas of the ray flowers. Fig. 86.—Dandelion. 1, two heads and a leaf (× ⅔); 2, a single flower (× 2); 3, fruit (× ⁸ ₃); 4, receptacle, with one fruit.