SCHOOL IN THE OPEN

Star (Christchurch), Issue 18450, 28 April 1928, Page 20 (Supplement)

SCHOOL IN THE OPEN

STUDIES IN THE GREAT OUT-OF-DOORS

(By

J. J. S. Cornes, 8.A., B.Sc.)

The “Star”-has arranged with Mr J. J. S. Comes, B A., B.Sc., to write a series of illustrated articles which will give teachers and others a fuller appreciation of the Great Out-of-doors. They will deal with various aspects of plant and animal life, as well as with inanimate nature. Questions and material -for identification will be welcomed.

AUTUMN fruits.

CCVII. In. autumn we see the beginning: of the end of many living creatures, but there are also preparations for the winter and for years to come. One autumn evening you sat looking down on a township from the hills above, and, as you watched, all the lights went out one after the other, though sometimes it was simply that the •blinds were drawn. You felt that the day was indeed over. But as you looked longer, there arose in your, mind the picture of banked-up fires, of things set in order for the morning, and of other prepara-

tions for a new day besides the chief preparation of rest. It is the same in the household of Nature. When we turn to fruits, however, we see preparations which are not so much for the individual as for the continuance of the race. In a sense they crown the plant’s work for the year, but their full meaning is not for the individual. They protect and scatter the seeds, but all that is in them is loss to the parent plant. A fruit is the part of the flower that persists and grows after pollination and fertilisation—that is to say, after the possible seeds or ovules have become real seeds. In most cases, a fruit may be described as the ripe ovary, i.e., seed-box, or as a collection of ripe seedboxes, with or without extra parts, such as the fleshy top of the flower-s talk or the remains of the calyx. In some cases, as in common cereals, where a single seed fills the seed-box, fruit and seed are almost identical—but the scientific difference remains clear. The wall of the ovary may be come a dry and haM seed-box, or a

succulent one. Let us think of the dry fruits we know First, there are nuts or nutlets (achenes), which' do not open to liberate the contained seed. In true nuts —-'hazel, oak, beech—there is a very hard fruit-wall (seed-box) to which the enclosed seed is not closely attached. In the fruits of buttercup, dock, sorrel (achenes), the wall is not hard, but still the enclosed seed does not adhere to it. In grains of wheat, maize, etc., the fruit wall is somewhat leathery, but this time the envelope of the seed is closely attached to it, i.e., seed-coat to seed-box. Second, there are the splitters, also not requiring to liberate their seed. They break into pieces, each of which

encloses one seed, and is equivalent to an achene. This holds for the fruits of hemlock and all Umbellifers, for wharangi (Melicope), for geranium,, mallow and for Labiates. It is enough to look into the fruit of a ripe dead-nettle to see that the fruit has neatly divided into four nutlet-like pieces, each enclosing a single seed. Sycamore and Maple are also Splitters. Third, there are the box-fruits, which must open in some way to scatter the seeds. Pea-pods and poppy-heads are good examples of pods and capsules. Turning from dry to juicy fruits, we find again three main kinds. First, > the stone-fruits or- drupes, which are fleshy fruits corresponding to nuts. Imagine not all the ovary wall to grow hard, as in nuts, but only its innermost layer (the “stone”), and you have a drupe. Thus in the plum, apricot, peach or cherry, there is a firm outside skin which keeps out bacteria and moulds—until it gets even a slight wound; then the fleshy pulp, which is all loss to the parent plant, but attracts the birds,

, which scatter the seed; and then the : very hard “ stone ” which effectively l preserves the “ kernel ” or seed within ' —a living embryo—from being digested in the bird’s food-canal, from being , frost-bitten in the ground, from prema- . ture sprouting and from other risks. 5 Second, there are berry-fruits, the fleshy forms corresponding to capsules 5 or box fruit. But here the innermost layer of the ovary wall must not grow ’ stony, for the same reason as that a - capsule must open. Tomatoes, goose- ■ berries, bull-bullis (porro-porro) are examples. Third, there are the pip-fruits, or pomes, e.g, apples, pears, 1 quinces. Whereas in a berry " the outer fleshiness is due to the 1 ovary-wall (seed-box) growing sort : throughout, in a pome the flesh is due • to the flower-stalk, the receptacle, growing up around the ovary-wall, which remains tough—the leathery core. Is there not a more stalky, woody taste about the flesh of pomes than that of berries? A berry is a softened capsule, b-ut a pome is a growu-over capsule. The core is the true fruit in a pome. All the above are “ simple ” fruits, where the flower had one carpel, or. at the most, one pistil, so that the fruit represents one seed-box or ripened ovary. The use of the fruit is to give the seed a good send-off in life. This needs looking into. 1. The seed is an embryo plant with a legacy of nutritive material; it grows within the ovary from the microscopic egg-cell of an ovule fertilised by a pol-len-grain. It is, for a time, a very deli- ‘ date )Oung life. One tise of the fruit is to protect the developing seed from lad weather. 2. Even when the seeds arc fully formed, and have got a good grip of life, there is need for the fruit’s protection against small seed-eating animals, such as boring beetles, or against birds and rodents, which devour and digest the seeds. 3. Not less important is the part fruits plav in seed-scattering, by explosion, by forming parachutes, by fixing on animals or by leing themselves eaten. 4. Even when the seed has been successfully scattered and sown, it may need the fruit’s protection on the ground. It may not be ready- to germinate, or the season for germinating may be months ahead. The enclosing fruit, or its innermost wall, must protect the seed from the frost and from the appe- I tite of many small animals that work underground. (To be continued next Saturday.)