styles, and by its two cells, as we shall see if we cut the Ovary across.

FIG. 17.-Vertical section of a flower of Cow Parsnip.

The calyx is superior, gamosepalous; corolla polypetalous, regular or irregular; stamens epigynous, pentandrous; pistil syncarpous, ovary inferior.

8. DAISY.-The structure of the flower-heads is very puzzling at first. Let us refer again to the Cow Parsnip. In this plant we have a number of flowers borne upon short peduncles (pedicels), which spring from the same point, or centre. Suppose all the flowers had been sessile, we should then have had them arranged upon the top of the stem, much in the same way as the parts of a single flower are arranged upon the floral receptacle. In the Daisy we have an example of such a case. Very numerous small flowers, called florets, are arranged upon a common receptacle, which in the Daisy is conical, and surrounded at its base by a whorl of small, narrow, herbaceous leaves, forming what is called an involucre, and reminding us much of a calyx, for which it is apt to be mistaken by beginners.

If a careful section be made lengthwise through the centre of the flower-head, the general plan of the whole becomes evident, though from the smallness of the florets in the Daisy a lens will be needed in order to make out their structure properly. The cut shows such a section.

There is a marked difference in form between the outer and inner florets of the flower-head, due to the onesided enlargement of the corolla in the former. The outer

FIG. 18.-Vertical section of a flower-head of Daisy. The outer florets with strap-shaped corollas form the ray, the inner, smail, tubular florets," the disk.

florets with one-sided, white corollas, taken together, form the ray of the flower-head; the smaller yellow florets, with regular corollas, occupying the centre of the head, form the disk.

In describing the structure of flower-heads (capitula), it is well to examine the ray and disk florets separately. Neither of these appears, at first sight, to have a calyx. Analogy, however, affords sufficient reason to conclude that each floret has its own calyx, but it is wholly adherent to the ovary. It is superior and gamosepalous. In many plants related to the Daisy-the Thistle for example-the upper, free portion (limb) of the calyx exists as a crown of fine bristles surrounding the top of the

ovary.

The corolla of the ray florets is (white) gamopetalous and irregular; of the disk florets (yellow) gamopetalous and regular. The stamens in the ray florets are absent or imperfect; in the disk florets they are five in number (pentandrous), and inserted upon the corolla. In consequence of this adhesion to the corolla they are termed epipetalous.

An important character which the stamens present is yet to be noted, but from the minuteness of those organs

it may be well to verify it in some plant with larger flower-heads, as the Dandelion (in which all the florets are irregular) or the Thistle (in which they are all regular).

FIG. 19.-Disk floret of Daisy, the corolla and cohering (syngenesious) anthers laid open.

It will be found that the stamens cohere by their anthers. On this account they are termed syngenesious. The coherent anthers form a tubular sheath which closely surrounds the style. The pistil we may infer to be syncarpous from the two-lobed stigma, notwithstanding that the inferior ovary is one-celled.

In the Daisy we have :-calyx superior, gamosepalous; corolla gamopetalous, regular (disk), or irregular (ray); stamens epipetalous, pentandrous, anthers syngenesious; pistil syncarpous, ovary inferior.

9. White and Purple DEADNETTLE.-Either will do. The cut represents the former, which has rather larger flowers. The calyx is free, but the sepals, five in number, as indicated by the five acute teeth, are coherent. The corolla is gamopetalous and irregular, the divisions being unequal. The stamens, easily found on pulling out a corolla from the calyx and cutting it open on the

side, are four in number, one stamen being suppressed. On this account the flower is said to be unsymmetrical, the symmetry, or agreement in the number of parts in each series of the flower-leaves, being interrupted. The stamens are adherent to the lower part of the corolla, consequently epipetalous, and two are long and two short, the lower

FIG. 20.-Vertical section of a flower of White Deadnettle.

;

and outer pair being longer than the upper and inner hence they are termed didynamous. The pistil is syncarpous, consisting of two carpels, as indicated by the bifid stigma, and the ovary is superior and deeply four-lobed, so that the style springs from the centre and base of the lobes of the ovary. Deadnettle has calyx inferior, gamosepalous; corolla gamopetalous, irregular; stamens epipetalous, didynamous; pistil syncarpous, ovary superior.

10. PRIMROSE, CowSLIP, or AURICULA.-Whichever may be most convenient. The calyx is free, the sepals coherent. The corolla regular, the petals coherent. Note carefully the position of the stamens with respect to the lobes of the corolla. We have already observed the tendency to alternation of parts which usually obtains in the arrangement of the floral organs, but here we find the

epipetalous stamens are opposite to the lobes (answering to the petals) of the corolla. If the anthers be low down in the tube of the corolla, carry a straight line up from one of the anthers, and it will be found to coincide with the

FIG. 21.-Vertical section of a flower of Primrose, the calyx being

removed.

middle of one of the 5 lobes of the corolla. This opposition of parts should always be noted when it occurs. In this case it is probably due to the suppression of a whorl of 5 stamens exterior to the whorl which is developed.

The pistil, from its centrical position, we may judge by analogy to consist of 5 coherent carpels, although the superior ovary is one-celled, and the carpels so completely consolidated as to leave no trace of lobing, even in the stigma. Primrose has calyx inferior, gamosepalous; corolla gamopetalous, regular; stamens epipetalous, pentandrous; pistil syncarpous, ovary superior.

II. STINGING NETTLE.-Either of our two native species. If the larger one be used it will' be needful to gather two specimens, carefully examining the minute flowers in order to ascertain that in one specimen they enclose stamens, in the other a pistil, because these organs occur in separate flowers (the flowers being imperfect, unisexual or diclinous), and in the Greater Nettle on