Nonvascular Plants

General CharacteristicsTHE PLANTS

What Are Plants?What Are Plants?

Traditionally: All the photosynthetic organisms plus Fungi

Fungi have been removed to a separate kingdom Prokaryotic photosynthetic “Blue-Green Algae”

removed to Bacteria (Cyanobacteria) Other “Algae” removed to the Protista

Plants probably evolved from certain Charophytes “Green Algae”

Characteristic Features of PlantsCharacteristic Features of Plants

Multicellular, with distinct tissues and organs Chlorophylls a & b; carotenoids Gametangia with outer non-reproductive cells that

protect developing gametes Developing embryo enclosed in a female reproductive

structure Alternation of generations Form phragmoplast and cell plate during cell division Starch is the primary food reserves in the chloroplast Cellulose is the principal component of the cell wall

Sporic MeiosisSporic Meiosis

MeiosisFertilizationSpores

- + - +

Sporophyte(Diploid individual)

Zygote

- Gamete+ Gamete

Gametophyte(Haploid individuls)

This cell undergo meiosis

Plants alternation of generations

1n

2n

Bryophytes: Nonvascular PlantsBryophytes: Nonvascular Plants

Early land plants, require water for fertilization Two characteristics distinguish them from vascular plants

a. Lack specialized vascular tissues but: Mosses have hydroids (water) and leptoids (sugar) Most Bryophytes have rhizoids (anchor)

b. The nature of alternation of generation Gametophytes are nutritionally independent Sporophytes are permanently attached to gametophytes Thus the gametophyte is the noticeable and dominant

generation

Bryophytes: HabitatsBryophytes: Habitats

Often abundant in relatively moist habitats A number of mosses are able to survive

severe temp. (also on bare rocks) Some mosses & liverworts are

predominantly aquatic Bryophytes are sensitive to air pollution

specially SO2 (indicators)

Liverworts: Phylum HepatophytaLiverworts: Phylum Hepatophyta

Thought that they cure liver diseases (Doctrine of Signature)*

Less conspicuous plants Their rhizoids are single celled unlike mosses Have numerous pores (associated with air

gaps) which function as stoma Gametophytes are Thallose or Leafy

LiverwortLiverwort

Thallose Liverworts (nonleafy)Thallose Liverworts (nonleafy)

The thallus is many layers thick, perennial Mostly unisexual e.g. Marchantia Male gametophytes produce antheridia on disk

headed stalks Female gametophytes produce archegonia on

umbrella headed stalks Sexual reproduction requires water Asexual reproduction by means of Gemma cups

Thallose LiverwortThallose LiverwortMarchantiaMarchantia

Return ♀♂

Gemmae in a LiverwortGemmae in a Liverwort

Life cycle of Marchanta

Leafy LiverwortsLeafy Liverworts The majority of liverworts (4000 species) are leafy Abundant in the tropics and subtropics Leaf as in mosses is one cell thick Leaves are arranged in two rows with a third of

reduced leaves* Monoecious (terminal archegonium & lateral

antheridium) Archegonium & the developing sporophyte are

covered by perianth

Leafy Leafy LiverwortsLiverworts

Nowellia curvifolia

N. Curyifolia sporophyteGametophte

Young sporophyte

By A. Nelson

Lophocolea heterophylla

Gametophyte

young sporophyte

Sporophyte

Leafy Leafy LiverwortsLiverworts

Mosses: Division Bryophyta *Mosses: Division Bryophyta *

True mosses are small inconspicuous plants Gametophytes are represented by

Leaves which are one cell thickHave multicellular rhizoids, Stoma are presentHave hydroids that resemble xylem tracheidsHave leptoids that resemble sieve elements

Sporophytes are photosynthetic Two patterns of growth: Feathery & Cushiony

MossesMosses

Atrichum undulatum

“Roof Moss”

Sporophyte with capsule

Gametophyte

Mosses morphology

Feathery Mosses

Feathery: Much branched, creeping Sporophytes are born laterally

Feathery Mosses

Cushiony mossesCushiony mosses

Gametophytes are erect and little branched Bear a terminal sporophyte

Atrichum undulatum

Gemmae in a MossGemmae in a Moss

Tetraphis pellucida

Gemmae

•Detach from parent gametophyte and grow into new gametophyte.

•An example of vegetative reproduction

Life Cycle of a MossLife Cycle of a Moss

Ecology of SphagnumEcology of Sphagnum Leaves consist of large dead cells with pores, readily

become filled with water Water holding capacity of the moss is 20 times its dry

weight (5 times cotton) They form extensive peat bogs in temperate regions Peat bogs cover 1% of world's land surface (~1/2 USA) Contribute to acidity of their own habitat (pH 4) Peat is formed from accumulation of the moss and

associated grasses and sedges In Ireland and other northern regions it is used as fuel