Bryophytes_prelab2.pdf

BOTANY 201 Laboratory Department of Biological Sciences College of Science University of Santo Tomas Tomas

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Moist-loving plants Pioneer species Small plants plan ts that has chlorophyll a & b, cell cell walls made up of cellulose, motile moti le sperms & starch (storage) (storage) Lack well-developed vascular tissues  absorb water by capillarity Lack true tru e roots, roots, stems & leaves Gametophyte – dominant; perennial Sporophyte – short-lived; unbranched; produces sporangium →

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Heteromorphic Alternation of Generation Gametophyte generation:  

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dominant stage Free-living & photosynthetic

Sporophyte generation:  

short-lived attached to and dependent on the gametophyte for nourishment  parasitic to the gametophyte →

Character

Thallophyte

single cells or filament of cells

Plant Body

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Gametangia

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unicellular and lacks a protective jacket of sterile cells

Brophyte

blocks or sheets of cells forming a parenchymatous tissue •

multicellular and have a protective jacket of sterile cells •

Primitive Features

Advanced Features

 Usually have no lignin  Have multicellular sex organs (i.e.: Small, low-lying, and generally gametes are enclosed by sterile moisture loving plants  jacket cells) No roots, only filamentous Are parenchymatous, not rhizoids filamentous Retain the zygote within the female sex organ & allow it to develop into an embryo there Have cutin on the plant and spores •

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LIVERWORTS

HORNWORTS

MOSSES

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Hepatics or liverworts rhizoids are always unicellular Thallus are dichotomously branched and exhibits dorsiventrality:  upper side – photosynthetic (chlorenchymatous cells & air chambers)  lower side – for storage & nonphotosynthetic (scales & rhizoids) Gametophytes are lobed & bilaterally symmetrical 1. Leafy 2. Thallose Unstalked sporangia Reproduce asexually

Life Cycle of Class Hepaticae

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Thallose liverwort Gametophyte: Flat, ribbon-like  Perennial; dichotomously branched  Unisexual 

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Gametophores:  Archegoniophore  Antheridiophore 

Male

Female

Gemma – multicellular asexual reproductive units

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Hornworts – long horn-shaped sporophytes

have the simplest gametophytes of the Bryophyta small, green thallus plants with little differentiation of  vegetative tissues. antheridia are located in roofed chambers in the upper portion of the thallus. archegonia are embedded within the thallus. sporophyte is different from that of the Hepaticae. foot embedded in the thallus serves an absorbing organ. The sporangium is an upright elongated structure.

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Mosses have specialized cells that conduct water and others that conduct photosynthate. Gametophytic generation – dominant; has two growth stages:  

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creeping filamentous stage (the protonema) from which is developed, The moss plant with an upright or horizontal stem bearing small spirally arranged green leaves.

Sporophyte – dependent on the gametophyte for survival. have disc shaped chloroplasts, lack pyrenoids and have stomata

Rhizoids are found at the base of the stem Gametangia occur at the tips of either the main or lateral branches

Moss Sporophyte

 Moss Gametophyte