What is "petioles"

Usage examples of "petioles".

The fact of so many organs of different kinds--hypocotyls and epicotyls, the petioles of some cotyledons and of some first leaves, the cotyledons of the onion, the rachis of some ferns, and some flowerstems--being all arched whilst they break through the ground, shows how just are Dr.

Here then the arching of the plumule plays the same part as in the case of the petioles of the Delphinium.

The fact of tubers being formed by the foregoing three widely distinct plants, makes us believe that their protection from animals at an early age and whilst tender, is one at least of the advantages gained by the remarkable elongation of the petioles of the cotyledons, together with their power of penetrating the ground like roots under the guidance of geotropism.

Owing to this rising of the petioles, and the vertical sinking of the large leaflets, the leaves become crowded together at night, and the whole plant then exposes a much smaller surface to radiation than during the day.

Filaments were therefore fixed horizontally to two hypocotyls close beneath the petioles of their cotyledons.

The petioles rise direct from the ground, and are from 5 to 7 inches in length.

Externally roothairs are formed on the confluent petioles, either a little above, or on a level with, the plumule.

Their petioles are completely confluent, forming a tube which terminates downwards in a little solid point, consisting of a minute radicle and hypocotyl, with the likewise minute plumule enclosed within the base of the tube.

As soon as the confluent petioles protrude from the seed they bend down, as they are strongly geotropic, and penetrate the ground.

The petioles are clothed with roothairs like those on a true radicle, and they likewise resemble radicles in becoming brown when immersed in a solution of permanganate of potassium.

The petioles protrude from the seeds soon after the autumnal rains, and penetrate the ground, generally in a vertical direction, to a depth of from 4 to even 6 inches.

But the seeds of the present species in germinating behave like those of Megarrhiza, excepting that the elongated petioles of the cotyledons are not confluent.

But in some instances they were fastened down by narrow strips of card, and in others by their petioles being passed through slits in the cork.

We may even infer as probable that the less or greater destruction during a frost of the leaves on a plant which does not sleep, may often depend on the greater or less degree of flexibility of their petioles and of the branches which bear them.

The blades are thin, and the petioles, which become much curved down at night, are short, so that here weight can hardly have produced any effect.