sábado, 5 de septiembre de 2009

Non-Vascular Plants

Non-vascular (lower) plants


1. Lack true conducting tissues, leaves and roots. Since they lack elaborate conducting tissues they are relatively small


2. Require water for fertilization so they must grow in moist or seasonally moist habitats

Mosses


Mosses are very small green plants. Typically they consist of a stem not much thicker than a thick hair, densely covered with leaves maybe 1/16th or 1/8th of an inch long. Often moss stems branch and rebranch. Usually many mosses grow together forming a thick green carpet. Sometimes this carpet is no larger than a dime, but other times it may cover areas several feet in diameter.

Pterophyta


The Pterophyta are the second largest division of the plant kingdom. There are 20,000 species of ferns compared to about 250,000 flowering plants alive today. Most ferns are herbaceous plants such as Polypodium virginianum (right) which grows in Ohio on damp rockfaces.

Vascular Plants


Vascular (higher) plants:

1. Have true conducting tissues (xylem and phloem), leaves, stems and roots
2. Constitutes the majority of plants

Gymnosperms


Gymnosperms- (“naked seeds”) A type of vascular plants which is more primitive than the flowering plants (angiosperms). Gynosperms commonly have seeds within a cone.