孢子体配子体BRYOPHYTES.PPT

BRYOPHYTES – 3. MOSSES Art/Science/Knowledge of Plant Biology 1. Sexual Reproduction in mosses gametophyte Rhizoid archegonium antheridium 精子器 颈卵器 BRYOPHYTES – 3. MOSSES Art/Science/Knowledge of Plant Biology Sexual Reproduction in mosses (cont’d) This mass of sperms is forced out of the top of the antheridium when it absorbs water. Rain is absolutely necessary After release, the sperm mass breaks up into individual cells, each with a pair of flagella. A sperm after swimming down through the archegonium neck, unites with egg forming 2n zygote. Zygote Embryo Sporophyte I. II. III. 蒴柄 蒴盖 孢蒴齿 藓帽 BRYOPHYTES – 3. MOSSES Art/Science/Knowledge of Plant Biology Sexual Reproduction in mosses (cont’d) I. II. III. Sporophyte 孢子体 The Moss Lifecycle 1 Referring to the diagram, the lifecycle of a typical moss can be explained by starting with the spores released from the moss capsule. If the spore falls on to suitable ground, it starts to grow and develops into a small green shoot called a protonema 原丝体. This protonema soon grows buds that become the familiar leafy green stems of a moss. This phase of the moss lifecycle is termed the gametophyte. Art/Science/Knowledge of Plant Biology I. The Moss Lifecycle 2 -Within some leaves of the gametophyte, special structures develop into male and female sex organs. -The male part is called an antheridium 精子器 and the female part the archegonium 颈卵器 -Inside the antheridium, sperm are produced. They possess tails allowing to swim, in a film of water, to the archegonium. - They are attracted to the archegonium by chemicals released into water. - Once reaching the archegonium they swim down its neck to reach and fertilize the egg within. Art/Science/Knowledge of Plant Biology II. I. The Moss Lifecycle 3 - The now fertilized egg develops into a structure called the sporophyte. The sporophyte consists of a stem/seta 蒴柄 and a capsule 孢蒴lots of spores are produced. - During the growth period when the seta is elongating and the spores gr