BIOL 2P93 Lecture Notes - Lecture 3: Polysporangiophyte, Motility, Xylem
7 May 2018
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Spring BIOL 2P93 Lecture 2 05/05/2018
Chapter 16: Bryophytes
• Oldest land plants
• Bryophytes
o Mosses, liverworts, hornworts
o Similar to one another
▪ They lack vascular tissues and seeds
▪ Plants in all 3 groups are haploid
o 3 plants are unique in that they live their lives w/ only 1 set of chromosomes
o Morphologically simple, not much more complex than their algal ancestors
o Piail sall leaf o flat plats loated i
▪ moist temperate/tropical forests
▪ along streams, wetlands
▪ dry desert areas on dry, hot, and exposed rocks
▪ north of the Arctic circle
▪ Mosses dominate plants on rocky slopes above timberline in mountainous areas
▪ Some can live in cold temperatures of Antarctica
▪ Few are aquatic (mostly freshwater)
o Tortula obtuissima
▪ Dry land moss
▪ Moisture obtained directly from external environment (dew/rain)
▪
o Campylopus sp.
▪ Moss in Antarctica
▪ Excellent dispersal techniques -> can reside in harsh habitats
▪
o Deep water aquatic moss found as a mat at the bottom of freshwater lake in Oregon, USA
▪
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Spring BIOL 2P93 Lecture 2 05/05/2018
o Ricciocarpos natans
▪ Floating liverwort found in still freshwater ponds/streams
▪
• Bryophytes: Evolutionary Relationships
o First evidence appears in Argentinian rocks ~ 488-444 mya w/ Liverwort cryptospore fossils
▪ Primitive terrestrial plant spores
o Other Bryophyte fossils resemble gametophores of the Liverwort Order Metzgeriales
▪ ~385-359 mya
▪ http://www.britannica.com/EBchecked/topic/82573/bryophyte/57928/Evolution-and-
paleontology
o Discovery of Liverwort cryptospores puts back the colonization of land by plants about 10
million years
▪ Confirms that Liverworts are likely ancestor of all plant
▪ Appearance of terrestrial plants is one of the most important evolutionary break-through in
Eaths histo
• http://news.bbc.co.uk/earth/hi/earth_news/newsid_9079000/9079963.stm
▪
• Liverwort cryptospores, evidence of the oldest land fossils found to date
o Found in Argentinian rocks ~488-444 mya
o Researchers not yet discovered fossils of the Liverworts that produced these spores
▪ Use of genetics has confirmed Liverworts as the ancestor for all land plants
▪ Eaied 3 itos DNA seuees i gees that dot ode fo poteis foud i many
plants
▪ After examining 352 species from all major groups of land plants, it was found that only 11
Liverwort species lacked introns
o Other plant groups, including Hornworts & other Bryophytes had at least two of the DNA swaths
▪ Most likely explanation fo Lieots lak of these itos is that the ee the oigial
land plants & other plants branched from them picking up the introns early on
• http://www.sciencemag.org/news/1998/08/liverworts-original-landed-gentry
o Bryophytes & Vascular Land Plants (VLP) share some characteristics w/ Charophytic Algae
o Bryophytes also have characteristics that are transitional in nature b/n Charophycean Green
Algae & VLP
• Charophytic Algae & Land Plants: Similarities
o Charophytes & Land Plants contain chloroplasts w/ well-developed green granules
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Spring BIOL 2P93 Lecture 2 05/05/2018
o Have asymmetrical motile cells w/ flagella extending from the side, not the end
o In the Cell Cycle Charophytic Algae & Land Plants exhibit breakdown of the nuclear envelope at
mitosis & persistent spindles of phragmoplasts during cytokinesis
o Chara & Coleochaete spp. exhibit oogamous sexual reproduction similar to Land Plants
o Coleochaete spp. zygotes are retained in the parental thallus, cells covering the zygotes develop
wall ingrowths similar to those at the gametophyte-sporophyte junction of Bryophytes (transfer
cells)
▪ These cells function in nutrient transport b/n gametophyte and sporophyte
• Charophytic Algae & Land Plants: Differences
o Land plants differ in 6 ways from Charophytic Algae
▪ 1) Male & Female gametangia (antheridia & archegonia) both have a protective sterile
jacket
▪ 2) Zygotic retention & development of multicellular embryo (sporophyte) w/n archegonium
of the female gametophyte
▪ 3) a multicellular diploid sporophyte, resulting in increased meiosis & spore production
following each fertilization event
▪ 4) multicellular sporangia consisting of a sterile jacket layer and internal spore-producing
(sporogenous) tissue
▪ 5) Meiospores w/ walls containing sporopollenin
▪ 6) Apical meristem tissue
o
• Bryophytes & VLP
o Even though Bryophytes are land plants, they are significantly different from the evolutionarily
advanced VLP
o Bryophytes are non-vascular
▪ Lack xylem & phloem
• Water & food conducting vascular tissue
o “oe Bophtes hae ate odutig tissues ut alls of ate odutig ells aet
lignified
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Document Summary
Algae & vlp: charophytic algae & land plants: similarities, charophytes & land plants contain chloroplasts w/ well-developed green granules. 05/05/2018: have asymmetrical motile cells w/ flagella extending from the side, not the end. Lack xylem & phloem: water & food conducting vascular tissue, o(cid:373)e b(cid:396)(cid:455)oph(cid:455)tes ha(cid:448)e (cid:449)ate(cid:396) (cid:272)o(cid:374)du(cid:272)ti(cid:374)g tissues (cid:271)ut (cid:449)alls of (cid:449)ate(cid:396) (cid:272)o(cid:374)du(cid:272)ti(cid:374)g (cid:272)ells a(cid:396)e(cid:374)(cid:859)t lignified. 05/05/2018: potential to become woody, both bryophytes & vlp exhibit alternating heteromorphic gametophytic & sporophytic generations in their life cycles. Not the un-branched sporophyte w/ a single sporangium which is depending on the gametophyte. Dominant sporophyte seen: bryophytes: evolutionary relationships, embryophyte cladogram which reflects the relationship b/n bryophyte lineages & b/n the. Bryophytes & polysporangiophytes: embryophytes which are advanced land plants have a multicellular embryo which is retained in the female gametophyte, cladogram shows that hornworts share a more common recent ancestor w/ polysporangiophytes than the liverworts or mosses. Liverworts are a sister group to all other.
