BOTANY 201 LaboratoryDepartment of Biological Sciences

College of ScienceUniversity of Santo Tomas

� Moist-loving plants

� Pioneer species

� Small plants that has chlorophyll a & b, cell walls made up of cellulose, motile sperms & starch (storage)

Lack well-developed vascular tissues → absorb water � Lack well-developed vascular tissues → absorb water by capillarity

� Lack true roots, stems & leaves

� Gametophyte – dominant; perennial

� Sporophyte – short-lived; unbranched; produces sporangium

� Heteromorphic Alternation of Generation

� Gametophyte generation:� dominant stage

� Free-living & photosynthetic

� Sporophyte generation:� Sporophyte generation:� short-lived

� attached to and dependent on the gametophyte for nourishment → parasitic to the gametophyte

Character Thallophyte Brophyte

Plant Body •single cells or filament of cells

•blocks or sheets of cells forming a parenchymatoustissue

Gametangia •unicellular and lacks a protective jacket of sterile cells

•multicellular and have a protective jacket of sterile cells

cells

Primitive Features Advanced Features

• Usually have no lignin• Small, low-lying, and generallymoisture loving plants• No roots, only filamentousrhizoids

• Have multicellular sex organs (i.e.:gametes are enclosed by sterilejacket cells)• Are parenchymatous, notfilamentousrhizoids filamentous• Retain the zygote within thefemale sex organ & allow it todevelop into an embryo there• Have cutin on the plant andspores

LIVERWORTS HORNWORTS MOSSES

� Hepatics or liverworts

� rhizoids are always unicellular� Thallus are dichotomously

branched and exhibits dorsiventrality:� upper side – photosynthetic

(chlorenchymatous cells & air chambers)(chlorenchymatous cells & air chambers)

� lower side – for storage & non-photosynthetic (scales & rhizoids)

� Gametophytes are lobed & bilaterally symmetrical1. Leafy2. Thallose

� Unstalked sporangia� Reproduce asexually

� Thallose liverwort

� Gametophyte:� Flat, ribbon-like

� Perennial; dichotomously branchedbranched

� Unisexual

� Gametophores:� Archegoniophore

� Antheridiophore

Male Female

Gemma – multicellular asexual reproductive units

� 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 � 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.

� Mosses have specialized cells that conduct water and others that conduct photosynthate.

� Gametophytic generation – dominant; has two growth stages:� creeping filamentous stage (the protonema) from which is

developed,The moss plant with an upright or horizontal stem bearing small 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 Gametophyte

Moss Sporophyte