AGE OF PLANTS

New Zealand Herald, Volume LXXI, Issue 21876, 11 August 1934, Page 8 (Supplement)

AGE OF PLANTS

VIGOUR AND STAMINA Plants of very slow growth attain finer quality as the years roll but it is otherwise with the great host of rapid-growing, soft plants, including the majority of herbaceous perennials, florist's flowers and bedding plants. Generally speaking, youth has everything in its favour, and while young plants grow with vigour, strength and stamina, producing fine flowers and foliage, old plants become either hollow in the crown or make weak growth, which will fall victim to many ills. There are exceptions to this rule, even in herbaceous plants, and permanent subjects are frequently spoken of as being left undisturbed for years. Paeonies are examples of this class, but leaving these varieties out of the question, there are hundreds of fibrousrooted and multi-crowned plants which quickly deteriorate if not lifted and propagated every three years. With the majority of these, examples of which are the Michaelmas daisies, phloxes and heleniums, it is the common practice to pull the roots to pieces and replant these. This metlwd answers well enough up to a certain point, but there is no doubt that in time, old stocks of plants which have been treated in this way, repeatedly lose something of their stamina and gradually fail to maintain high quality. Plants from Cuttings Those growers who are observant are aware that plants propagated from cuttings, produce better fiowerß than divisions, and it is no Becret that the most successful exhibitors do a great deal of propagation by means of cuttings for the production of their show flowers. One needs but to put to a practical test the idea of striking young growths of phlox and Michaelmas daisies, instead of relying on old clumps to be convinced that there is something more than mere theory or fancy in the claim that cuttings are best. These and many others, will root freely in a cold frame in spring, and if a few are struck and planted beside a batch of root divisions the comparison will show a striking difference when it comes to flowering time. The same thing applies to violas and aubretias. The difference in size, colour, and brightness of the flowers is most marked in the plants from cuttings. These remarks are not to be taken as suggestive that nothing should ever bo spat up which may be obtained from cuttings. Such an idea would be folly, as many gardeners will be able to prove that they have practised the usual method of division without any sign of failure, but if one grower adheres exclusively to the old method of division and another grower annually strikes a batch or two of cuttings, the latter can, at any time, Bhow better and more substantial flowers than the former. Recently, a successful grower ot early-flowering chrysanthemums considered it a waste of good space to pull apart the young growths that issue from the roots. The reputed advantage of using those shoots which have already rooted he had proved a fallacy. The green shoots, cut off below a joint, make even progress, whereas the others are apt to stand still as though the sap flow was impeded at some spot where the stems'were hardened by cold weather.

VEGETABLE CATERPILLAR t

LIFE CYCLE EXPLAINED The vegetable caterpillar,, that interesting combination of the insect and plant kingdoms, occurs as a result of the caterpillars being parasitised by a fungus.- The genus Porina, which is most often attacked, is the well-known "subterranean grass caterpillar, which is the larvae of the greywh brown moth, so plentiful in the earnings of early summer. These caterpillars are infected by the spores of the fungus Cordyceps, of which Kobertsii is the best known species in New Zealand. Inoculation takes place during the life of the caterpillar, by the spores coming into contact with the body of the insect. Ihe germinating spore pierces the tissues and the mycelium of the fungus spreads through the interior and destroys the structure. The caterpillar dies and becomes the semi-woody vegetable caterP 'Vhe next stage is the fruiting stage, as fungi need to produce fruiting bodies to reproduce their kind. A long, slender stalk grows up usually from tlie head of the caterpillar, but mav apponr from the tail end as well, llie stalk of Cordyceps Robertsn may be from (Jin. to ]2in. lone, and the tip has & clubbed form which carries the sclerotia, or fruiting bodies. These bodies are filled with myriads of spores, which are distributed by the agency of moisture, and serve to infect other caterpillars. The genus is widespread all over the world, the Australian and New Zealand species being among the lamest.

Earlier writers regarded various species as insects which changed into plants. Watson, describing a West Indian species in 17(33, writes that in the spring it buries itself in the ground and commences to vegetate. By the middle of summer the tree arrives at full growth and resembles a coral branch* and is about 3in. high. Tli o plant then bears little pods, which, dropping off, become worms, ana then flies. This fantastical idea still persists in some localities. Another species of which there are records is Cordyceps sinensis, a celebrated Chinese drug.