Bryophytes

Lecturer: Asst. Prof. Dr. İsmail EKER

General characteristics of bryophytes• Bryo- gr. moss. & ~16,000 species.

• Non-vascular plants

• Advancements over algae: cuticle, multicellular gametangia, stomata

• Habitat: they require moist environment for active growth and sexual reproduction

• The diverse bryophytes are not a monophyletic group. Several lines of evidence indicate that these three divisions diverged independently early in plant evolution, before the origin of vascular plants.

• Mosses are the bryophytes most closely related to vascular plants.

• The gametophyte is the dominant generation in the life cycles of bryophytes

• Note, the name Bryophyta refers only to one division, but the informal term bryophyte refers to all nonvascular plants.

Bryophytes are represented by three phyla:

Hepatophyta – liverworts;

Anthocerophyta – hornworts;

Bryophyta - mosses

• the largest and most diverse divison of bryophytes, with more than 9,000 species.

• has green “leafy stems” and root-like structures called rhizoids, for anchoring (not true roots!), and leaf like structures (phyllids)

• absence of vascular tissue prevents bryophytes from having true roots, stems or leaves.

• some mosses such as members of the Polytrichaceae family contain

- Hydroids-transporting water and minerals

- Leptoids-transporting sugars and other nutrients

Division Bryophyta (Mosses)

gam

etop

hyt

esp

orop

hyt

e

(phyllid)

Bryophyte reproduction• Sexual and asexual

• Asexual reproduction by fragmentation and gemmae.

• Gametophyte plant (n) produces multicellular sex organs: Archegonia – produces egg (female) and Antheridia – produces motile sperms (male)

• Motile biflagellated sperm must swim to archegonia.

• Sporophyte (2n) occurs after egg is fertilized by sperm. Sporophyte matrotrophic and short lived (6-16 weeks).

• Sporophyte grows in the archegonium of the gametophyte plant – it’s dependent on it

• Mature sporophyte consists of: Foot (point of attachment), Seta (stalk), Capsule (spore case)

• Sporocytes within the Sporophyte undergo meiosis to produce a single kind of haploid spore

• If spore lands on suitable place, it will germinate into a protonema, the initial stage of the gametophyte plant.

Bryophyte sexual reproduction

sporophyte

Gametophyte with orange antheridia

Gametophyte with excised leaves making visible the sporophyte with embedded foot.

Gametophyte and attached sporophyte

gametophyte

• The male plant produces clusters of elongate antheridia which contain thousands of flagellated sperm.

Gametangia and gametes can be embedded in the gametophyte tissue as shown here, or attached at the surface of the gametophyte.

Antheridium (Sperm-bearing Organ) with an outer row of sterile (nonsperm-forming) cells enclosing inner fertile cells, each of which becomes a sperm gamete.

Gametangia –organs that produce gametes.

• The female produces vase-shaped archegonia, each containing a single egg.

Archegonium (Egg-bearing Organ) with a long neck extends beyond the venter, capped at the tip with cover cells.

Moss spore capsule (Tortula muralis var. muralis) SEM

Coloured scanning electron micrograph (SEM) of part of the opening mouth of a capsule (spore case) of moss. Mosses reproduce by means of spores at certain times during their life cycle. The spores are dispersed from the mouth of the capsule, dispersal aided by the wind. Magnification x1380

Sphagnum sp.

Polytricum sp.

Tortula sp.

Marchantiophyta (Hepaticophyta)- liverworts• Hepato- gr. liver. & 6,000 species.

• Gametophytes thalloid or leafy, often bilaterally symmetrical and lobed

• Simplest of all living plants.

• Rhizoids single celled.

• Reproduction:

- Asexual- with pieces of tissue call gemma, which are bounced by rain out of gemma cups.

- Sexual- haploid gametophyte, diploid sporophyte

• Sporophytes without stomata, but have pores.

• Specialized conducting tissue absent.

• Sporangium with dehiscent capsule, elaters present in some to disperse spores.

• Most cells contain numerous chloroplasts.

• Habitat- moist, some aquatic, temperate and tropical. Examples- Marchantia and Riccia.

• asexually with pieces of tissue call gemma, which are bounced by rain out of gemma cups.

gemma cups

Reproduction of Marchantiophyta

Antheridiophore

Antheridial stalk

Antheridial head

Male reproductive "umbrella"

Archegoniophore

Archegonial stalkArchegonial head

Female reproductive "umbrella"

the sporophyte generation consists of a small stalk with a podlike capsule, the sporangium, on top.

Marchantia sp.

Anthocerotophyta- hornworts• Antho- gr. flower, keras- gr. horn. & 100 species

• Hornworts are similar to liverworts except each cell only has one large chloroplast rather than many smaller ones, and the sporophytes are elongated capsules.

• Rhizoids single celled.

• Gametophytes thalloid.

• Specialized conducting tissue absent.

• Sporophytes with stomata.

• Sporangia dehisce to disperse spores, elater-like structures present.

• Habitat- moist temperate and tropical.

• Example- AnthocerosMagnification approximately 200x

The long, slender sporophyte generations grow upward from the thallus and are typically 0.5 to 12 centimeters in height.

Hornworts often have long, pointed sporophytes (resembling horns) that rise from the thalloid gametophytes.

Reproduction of Anthocerophyta

Anthoceros sp.

Bryophyte significance• Bryophytes are small and inconspicuous, but important part of the biosphere

• Food for mammals, birds

• Important to prevent soil erosion along streams

• Commercially – peat moss (Sphagnum) is used as fuel, soil conditioner, by florists, also it is used in potting soil for better water-holding capabilities. Its organic materials does not decay readily because of resistant phenolic compounds and acidic secretions that inhibit bacterial activity.

• Sphagnum has been used in the past as diapers and a natural antiseptic material for wounds.

• Today, it is harvested for use as a soil conditioner and for packing plants roots because of the water storage capacity of its large, dead cells.

• Peatlands, extensive high-latitude boreal wetland occupied by Sphagnum, play an important role as carbon reservoirs, stabilizing atmospheric carbon dioxide levels.

• Ethnobotanically- Liverworts look like liver. They were used as medicine to help the liver in the middle ages in Europe because of this.

• May 8th, 1950 the police in Silkeborg received an alarming message. On the previous Saturday a body had been discovered in a bog close to Bjældskovdal, an area located approximately 10 kilometres west of Silkeborg/Denmark. Accordingly, the body was discovered on May 6th, 1950.

• The Tollund Man was alive during the first part of the iron age, 300-400 years B.C.

• The antibiotic effect of Sphagnum moss prevent decay of it with humic acid (alsom known as "bog acid”. The acid in the peat, along with the lack of oxygen underneath the surface, had preserved the soft tissues of his body.

• at the Silkeborg Museum of Denmark

http://www.tollundman.dk/

Tollund Man