माध्यमिक विकास के लिए जिम्मेदार अधिकांश संवहनी पौधों में xylem और phloem के बीच ऊतक की एक प्रारंभिक एक-सेल परत

Noun:

केंबियम,

cambium's Usage Examples:

In many annual plants no cambium is formed at all, and the same is true of most perennial Pteridophytes and Monocotyledons.

primary phloem can be recognized with certainty in favourable cases, the question of the formation of secondary phloem by the cambium is not yet fully cleared up. In the Lepidodendron fuliginosum of Williamson, shown by its leaf-bases to have been a Lepidophloios, the secondary wood is very irregular, and consists largely of parenchyma.

The primary structure f ` is only found unaltered in the 1 1, 1 ` by means of a cambium set in very Il 111/1/1, 1 1 early, xylem being formed internally and phloem externally in a perfectly normal manner.

In favourable cases remains of the cambium are found on the outer border of the wood, and phloem is also present in the normal position, though it does not seem to have attained any considerable thickness.

It has been recently shown that several cambium-zones may remain in a state of activity, so that the formation of a new cambium does not necessarily FIG.

An ordinary cambium is scarcely ever found in the Monocotyledons, but in certain woody forms a secondary meristem is formed outside the primary bundles, and gives rise externally to a little secondary cortex, and internally to a secondary parenchyma in which are developed numerous zones of additional bundles, usually of concentric structure, with phloem surrounded by xylem.

Such meristematic layers are called secondary meristems. There are two chief secondary meristems, the cambium and the phellogen.

The in Stems. bundles of plants which form cambium are, on the contrary, called open.

The activity of the new cambium is often associated with the stoppage of the original one.

Wood thus altered is known as heart-wood, or duramen, as distinguished from the young sap-wood, or alburnum, which, forming a cylinder next the cambium, remains alive and carries on the active functions of the xylem, particularly the conduction of water.

cambium's Meaning':

a formative one-cell layer of tissue between xylem and phloem in most vascular plants that is responsible for secondary growth