What is some of the characteristics of Phylum Coniferophyta?

Answer 1

The Coniferophyta is a relatively large

group of plants which forms the dominant component of vast ecosystems, especially in the northern hemisphere (Northern Boreal Forest). Some of these plants are the largest organisms on the planet and also have the greatest longevity. This taxon is represented in the Southerh Hemisphere as well, especially in New Zealand.

The most significant vegetative adaptations of this taxon includeSecondary Growth and the production of protective Buds.

They also have a significant amount of internodal elongation which allows them to grow faster than the other plants we have reviewed.

Their Leaves have a battery of adaptations which foster survival in extreme habitats. Many of these traits are "Xeromorphic".

The "tree line" in the northern hemisphere is the conifer line as these are the most tolerant woody plants with regard to heat, cold, aridityand combinations thereof.

Link to Secondary Growth

Secondary Growth is the result of Lateral Meristems (Vascular Cambium & Cork Cambium). The word Cambium signifies themeristematic nature of these two.

The plane of cell division in both is predominately Periclinal (parallel to the surface). This produces radial files of cells which increase the girth of the organ in which they occur.

There are also some Anticlinal (Perpendicular to the Surface) cell divisions which increasethe circumference of Lateral Meristems. This is necessary to compensate for theincreased girth caused by increases in secondary vascular tissues and cork. Otherwise, secondary growth would produce interrupted sectors with deep cracks (little secondary growth) and elevated areas (lots of secondary growth).

The Vascular Cambium is a continuation of the Procambium. However, itinduces cambial activity in adjacent cells and thus further adds to itscircumference.

The Cork Cambium arises de novo (new) from Parenchyma cells.

The Vascular Cambium produces

Secondary Xylem (wood) and

Secondary Phloem (inner bark).

Secondary Xylem provides structural support but it also provides a conduit for thetransport of water throughout the entire plant.

It also provides a water reservoir! Water can accumulate in the "heartwood" so that it becomes available for transport in the "sapwood" if there is insufficient water coming from the roots.

The largest conifers are several hundred feet high and their root systems are equally large if not of greater extent.

The Tracheary Elements in conifers are

Tracheids. These serve the dual functions of the secondary xylem but they represent a compromise in terms of both.

Tracheid properties differ depending on the environmental conditions under which they are formed.

Tracheids have a thicker wall and a narrower diameter if they are formed during periods of water or temperature stress. The opposite occurs during times of plenty.

The former tracheids are better for support.

The latter tracheids are better for conduction.

Angiosperms produce Vessel Members and Fibers in their Secondary Xylem. These aremore specialized for conduction or support, respectively, and are, thus, more efficient at both.

Secondary Phloem transports sucrose

throughout the organism. Its Sieve Elements in the Coniferophyta areSieve Cells. These have Sieve Pores in their walls. They are lined withCallose and they are similar to sieve cells in seedless vascular plants.

Angiosperms have Sieve Tube Members which are more efficient for conduction.

The Cork Cambium (Phellogen) produces Cork (Phellem). Cork is commonly known as "outer bark". This tissue is dead, except for the Phellogen and its immediate derivatives. The walls of Cork Cells are impregnated withSuberin. This is a hydrophobic material that is water-proof andpathogen-proof.

It prevents excess water loss and it also insulates living cells from the externalenvironment. Some plants like Douglas Fir and Ponderosa Pine have barks which protect them from prairie fires. This allows them to survive in environments which are hostile to their competitors.

The Apical Meristems of Conifers are multicellular. They have much in common with the apical meristems of flowering plants. They do not have noticeable "Initials".

The Shoot Apical Meristem has a prominent Quiescent Center which has been called the Central Mother Cell Zone.

The Root Apical Meristem tends to be broad and all of the tissues of the Root Body and Root Cap are produced by the same Meristem Proper.

Answer 2

Phylum Coniferophyta includes plants like pine trees, spruce, and fir. They have needle-like or scale-like leaves, produce cones for reproduction, and are typically evergreen. Conifers are adapted to colder climates and tend to have a conical shape to shed snow easily.

Answer 3

Coniferophytas have woody stems. They also often have narrow leaves shaped as needles. These plants produce seeds in cones.