1. Introduction to the Non-Tracheophytes
Classification
Divided into 3 phyla
Hepatophyta, liverworts
Anthocerophyta, hornworts
Bryophyta, mosses
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2. Characteristics of Non-Tracheophytes
these are land plants with clearly visible alternation of generations.
they are howe not well adapted to live on land; hence they need to be on moist and shady habitats.
gametophyte generation is dominant, photosynthetic and nutritionally independent
do not have the vascular tissue - hence Nontracheophytes or Non-Vascular plants
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3. Non-tracheophytes…
they are low-growing plants because they do not have any strengthening and conducting tissue
they have no roots, stems and leaves, but rhizoids, caulidia and phyllidia respectively.
free water is essential for sexual reproduction
the male gamete swims to the female gamete by chemotaxis, so sexual reproduction can only occur in wet conditions
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4. Non-tracheophytes… gametes are produced in sex organs called:
antheridia - produce sperms
archegonia - produce eggs (ova)
sexual reproduction is oogamous, i.e., only the male gamete is mobile and fertilisation takes place in the archegonium
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5. Non-tracheophytes
sporophyte comprises a foot, stalk (seta) and capsule (sporangium)
may or may not be photosynthetic but is nutritionally dependent on the gametophyte and permanently attached to it
spores are borne in a capsule and are produced by meiosis, hence haploid
dry conditions are necessary for spore dispersal
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6. Nontracheophytes… they carry out asexual reproduction by:
Fragmentation
the production of minute bodies called gemmae, which give rise to new plants
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7. Characteristic features used to distinguish between the different phyla of Non-Tracheophytes
Differences in the three Non-tracheophyte phyla are based on:
the nature of the plant body, whether it is:
Thalloid - a multicellular body not differentiated into stems, root and leaves OR
Leafy - whether the plant has caulidia, phyllidia and rhizoids, and thus resembling a true plant.
the nature of the phyllidia (if present)
development of the juvenile phase of the gametophyte (protonema)
the presence or absence of an opening mechanism in the capsule
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8. 1. Phylum Hepatophyta (Liverworts)
called liverworts because
they were thought to resemble the liver
and the believe that they could cure any liver ailments.
This is thought to be the most primitive of the Non-tracheophytes
Gametophyte:
maybe thalloid or “leafy”.
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9. Phylum Hepatophyta…
germinating spores either develop directly into the gametophyte with no protonema or with a very reduced protonema
rhizoids are unicellular
Sexual reproduction:
the sex organs are either found embedded on the upper surface of the thallus,
or on special branches, archegoniophores and antheridiophores.
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10. Hepatophyta…
in Marchantia polymorpha, gametophytes either male or female, i.e., the species is dioecious.
in Riccia, male sex organs antheridia and archegonia are embedded on the same gametophyte, i.e., it is monoecious.
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11. Liverworts… Sporophyte
Simple, made up of foot, seta and capsule (sporangium)
Haploid spores produced in the capsule by meiosis
Other cells called elaters also present in the capsule
Spore Dispersal:
dehiscence of capsule is by elaters
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12. Phylum Anthocerophyta (Hornworts)
formerly included with the Hepatophyta because of their thalloid nature
now placed in a separate phylum, mainly on the account of their unique sporophyte.
Gametophyte
the hornworts have the simplest gametophyte of the Nontracheophytes.
they are always thalloid, with numerous unicellular rhizoids growing from the lower surface.
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13. Anthocerophyta…
there is a single large chloroplast per cell in the thallus.
there is no protonemal stage.
Sexual Reproduction:
the sex organs are embedded in the upper layer of the thallus
numerous antheridia in a single antheridial chamber.
antheridia similar in structure to the Hepatophyta
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14. Anthocerophyta… the archegonia are embedded within the thallus.
Have unique sporophyte
the capsule is needle-shaped (or cylindrical) rather than spherical like those of other Non tracheophytes.
when ripe the capsules split from the tip downward into two halves.
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15. Phylum Bryophyta (Mosses)
Gametophyte:
germinating spores of mosses do not develop directly into leafy gametophyte but go through the protonemal stage.
The protonema is anchored by rhizoids to the substrate
rhizoids are multicellular
gametophytes are “leafy”, never thalloid
the “leaves” are spirally arranged on the caulidia
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16. Bryophyta Sexual Reproduction:
gametophytes of many mosses are monoecious (homothallic), i.e., both antheridia and archegonia are produced on the same gametophyte.
some mosses are dioecious (heterothallic), i.e., antheridia and archegonia are produced on separate gametophytes
antheridia and archegonia develop at the apex of the leafy gametophyte
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17. Mosses… the sex organs occur in clusters referred to as:
an archegonial head or an antheridial head
the sex organs are separated by structures called paraphysis (ses)
the antheridial head are in turn enclosed by special leaves called perigonia
similarly the archegonial head is enclosed in perichetia
only one archegonium is fertilised per head.
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18. Mosses… Sporophyte Made up of a foot, a seta and a capsule
Capsule often covered by operculum
Capsule may be photosynthetic
Spores produced by meiosis
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19. Mosses… Spore Dispersal:
capsule of sporophyte has an elaborate mechanism of spore dispersal, dependent on dry conditions and involves the use of peristome teeth
Basic mechanism with some variations
The operculum, (which covers the capsule) falls off, to expose peristome teeth which surround the mouth of capsule
Peristome teeth open
Spores released and dispersed by wind
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20. Life cycle
Generalised life cycle of non-Tracheophytes.
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