Moss systematics and evolution

bryophyta orders

45

bryophyta families

115

bryophyta genera

900

bryophyta species

12,000

Bryophyta protonema

well developed

Bryophyta gametophore

leafy

Bryophyta leaves

often with multilayered midrib, unlobed, with differentiated alar/basal/marginal cells

Bryophyta oil bodies

absent

Bryophyta paraphyses

sterile filaments among gametangia

Bryophyta rhizoids

multicellular, often pigmented

Bryophyta seta (4)

relatively persistent

thick walled cells

conducting tissue

elongates before spore maturation

Bryophyta capsule covered by

calyptra

Bryophyta pseudoelators

absent

Bryophyta capsule wall (2)

multilayered

with stomata

Bryophyta capsule opening

usually by apical operculum

Bryophyta spores released

gradually from the capsule, typically via hygroscopic peristome

Bryophyta spores mature

simultaneously

sister relationship between liver worts and mosses is important because (2)

means that the absence of stomata in liverworts is likely the result of secondary loss, rather than ancestral absence.

It also implies an origin of stomata prior to the divergence of tracheophytes and bryophytes (c. 495–515 mya) and therefore the presence of stomata in the common ancestor of all living land plants

stomata are absent in

all liverworts as well as several genera of mosses, including the earliest diverging lineages of mosses and certain genera of hornworts.

number of independent losses of stomata in mosses

over 60

groups with pseudostomata

Sphagnales

examples groups without stomata (3)

Takakiales

Andreaeales

Archidiales

example groups with some non stomatal species (3)

Polytrichales

Grimmiales

Dicranales

moss gametophore development (2)

modular

each module arises from single apical cell

moss evolution began

more than 450 mya

Takakiopsida order/family/genus

1

Takakiopsida species

2

Takakiopsida network

system of rhizomes (without rhizoids)

Takakiopsida leaves

composed of 1–4 hollow cylindrical segments

Takakiopsida symbiosis

secrete mucilage that fosters fungi and nitrogen-fixing bacteria

Takakiopsida gametogangia

lacks paraphyses

Takakiopsida capsule (2)

without stomata

1 spiral slit

Sphagnopsida order

1

Sphagnopsida families

3

Sphagnopsida genera

4

Sphagnopsida species

150-300 spp

Sphagnopsida protonema

thallose and filamentous

Sphagnopsida leaves (3)

spirally leaves with fasciciles of branches

leaves without midrib

dimorphic (stem/branch leaves)

Sphagnopsida capitulum

short crowded branches at apex

Sphagnopsida cells

hyalocytes and chlorocytes

Sphagnopsida network

mature gametophores without rhizoids

hyalocytes (2)

clear, dead cells that lack chlorophyll

water absorption

chlorocytes

specialized, chlorophyll-rich cells found in mosses that are primarily responsible for photosynthesis

Sphagnopsida gametangia

without paraphyses

Sphagnopsida seta

absent, haploid pseudopodium

Sphagnopsida dispersal

explosive capsule dehiscence from operculum

Sphagnopsida capsule lacks

peristome

Sphagnopsida stomata

non function pseudostomata

Sphagnum diversification (2)

relatively recent (15-19 Mya)

associated with Miocene climatic cooling

Andreaeopsida orders

2

Andreaeopsida families

2

Andreaeopsida genera

2

Andreaeopsida spp

100

Andreaeopsida leaves (2)

with/without midrib

darkly pigmented

Andreaeopsida cells (2)

thick walled

isodiametric

isodiametric

having equal or nearly equal dimensions, widths, or diameters in all directions

Andreaeopsida gametangia

with paraphyses

Andreaeopsida seta

pseudopodium

short seta in Andreaebryum

Andreaeopsida capsule (2)

opens by 4 longitudinal slits

stomata absent

Andreaeopsida habitat

epilithic montane of acidic (sometimes basic) substrates

Oedipodiales family/genus/species

1

Oedipodiales phylogeny

uncertain, sister group to all peristomate mosses or basal Polytrichopsida

Oedipodiales seta

hyaline

Oedipodiales capsule (3)

with differentiated operculum

without peristome

stomata present

Polytrichopsida order numbers

2

Polytrichopsida families

2

Polytrichopsida genera

30

Polytrichopsida spp

310

Polytrichopsida habitat

terricolous

Polytrichopsida peristome

nematodontous

nematodontous

onsists of solid, unjointed teeth made from whole, dead cells with thickened walls

arthrodontous peristomes

formed by remnants of cell walls

transverse septa

Polytrichopsida peristome teeth

formed from entire amphithecium cells

amphithecium

the outer layer of cells in the developing embryo (sporophyte)

Polytrichopsida cell walls

uniformly thickened cell walls

Dawsonia

Polytrichopsida

peristome is numerous, hair-like (filiform) teeth that are inserted in multiple concentric rows

Polytrichales family

1

Polytrichales genera

27

Polytrichales species

300

Polytrichales protonema (2)

filamentous

sometimes persistent

Polytrichales gametophyte (2)

erect, up to 60 cm tall

most complex among mosses

Polytrichales conducting tissues

well developed

strand of hydroids and leptoids in stem/leaves/seta

hydroids (2)

 thin walled, elongate cells that have diagonal and porous end walls

specialized, non-lignified water-conducting cells found in the gametophyte generation of mosses

leptoids

elongated food-conducting cell like phloem

Polytrichales leaves (2)

robust midrib

often with photosynthetic lamellae

Polytrichales capsule

stomata present

Polytrichales peristome

16-64 nematodontous teeth

Polytrichales spores (2)

very small

produce tens of millions

Polytrichales CZ (2)

4-5 genera

19 spp

Tetraphidales structure (2)

small

acrocarpous

Tetraphidales protonema (2)

filamentous

with club-shaped/spatulate gemmiferous discs

Tetraphidales gametophore density

can induce interseasonal sex change

Tetraphidales capsules

with or without stomata

Tetraphidales peristome

nematodontous

4 erect, non-hygroscopic teeth

Bryopsida (3)

largest group of mosses, ~95% of all spp

leptoids not differentiated

arthrodontous peristome (if not reduced)

Arthrodontous peristome primary number of teeth (3)

haplolepidous

16

can be secondarily divided or fused

septa (3)

defining feature of arthrodontous peristome

joints/articulations

thickened horizontal cell wall remnants

arthrodontous peristomes formed from (4)

3 layers of amphithecium:

outer peristomial layer

primary peristomial layer

inner peristomial layer

exostome

outer ring of peristome teeth

exostome is made from (2)

outer peristomal layer

primary peristomal layer