Plant Biology Lecture: Plant Form, Function, Diversity, PDF

2/8/2025 -angiosperms co-evolve with insects PLANT FORM, FUNCTION AND...

2/8/2025 -angiosperms co-evolve with insects PLANT FORM, FUNCTION AND DIVERSITY Today’s Learning Objectives Descr ibe th e e vo lutionary histo ry of Land Pla nts Descr ibe and ide nti fy d iffere nces be tween mon ocots and d ico ts Descr ibe economically important plant sp eci es in terms of the ir b ota nic “a ffiliation ” a nd origin s Expla in the re aso ns for th e success of spe cific p lant gro ups in e vol uti onary histo ry and g eogra phic distribution -land plants evolve from green algae Phylogeny of the Land Plants -vascular plants have vessels that are used in bulk flow -seed plants have seeds and pollen -seed plants are independant from water for fertilization 1  2/8/2025 Ch a p te r 2 7 A cti ve L ec tu re Sl i d e 9 Diversity of Land Plants -most diverse group of plants are angiosperms -Most bryophytes are moses, disperse by spores (no seeds) -gymnosperms means naked seed Plant Phylogeny -angiosperms didnt evolve until mesozoic era -grasses are the most important food source for humans -should know when each group appears on fossil record -has a haploid generation, and it produces gametes by mitosis Plant reproduction involves an -gen 1 is haploid generation, gen 2 is diploid alternation of haploid and diploid generations generation -animals dont have two multi-cellular generations plants do 2  2/8/2025 -absorbs nutrition through the body of the plant Bryophytes not root, found in moist enviromets Bryophytes are small. do not produce roots. are haploid dominant. reproduce by unicellular spores rather than seeds. Bryophyte Specialization Ch a p te r 2 7 A cti ve L ec tu re Sl i d e 1 5 -peat bogs store carbon and keep it from Sphagnum Moss returning to atmosphere. Sp ha gn um mo ss ha ve sp eci al ize d cel ls tha t ho ld on to wate r, l ike a spo ng e. The y secr ete pr oton s th at ac idi fy th e su rrou nd in g wa ter an d p rod uce p he no ls tha t sl ow d eco mp osi ti on. Pe at bo gs store la rge a mo unts o f o rga ni c ca rbo n an d a re im por ta nt to the ca rbo n cyc le. 3  2/8/2025 Glo bal distr ibution of P eat-lan ds -peat bogs are non vascular plants ht tp:// co mm ons.wikim edia.or g/wiki/ File :Peat _cu tting s_n ear _Un asa ry_ -_g eo gra ph.or g.u k_-_1 76 303.jpg Bob Jones Vascular Plants -Vascular plants have Xylem and phloem 4  2/8/2025 Ch a p te r 2 7 A cti ve L ec tu re Sl i d e 1 6 -sporangium is where spores are produced for Fossil Record of Earliest Vascular dispersal Plants Vascul ar plants first app ear in th e fossil record 425 milli on ye ars ag o. The evolution of xylem and p hloem gave vascu lar plants a n advan tag e in size and hydra tion. Fossil Lycophytes roots and leaves well-defined tissue layers meristematic tissue that will eventually give rise to all tissues of the plant body -modern lycophytes are smaller Lycophyte Diversity Fossils indicate that the leaves and roots of lycophytes evolved independently from those of other vascular plants. A distinctive feature of lycophyte leaves is that they have only a single vein. 5  2/8/2025 Lycophyte Diversity Lycopodium Isoetes Giant Lycophytes http://www.uni-muenster.de/GeoPalaeontologie/Palaeo/Palbot/ewald1.htm -were called coal swamp forests because when Giant Lycophytes they get buried they become coal Swamps that formed widely about 320 million years ago were dominated by tree-sized lycophytes. 6  2/8/2025 -some ferns you can see stems but not all Ferns Ferns have distinctive leaves that uncoil during development from tightly wound “fiddleheads.” Many ferns seem to only be made up of leaves because their stems remain underground. Horsetails The horsetails, represented by 15 living species, produce tiny leaves arranged in whorls, giving them a jointed appearance. Horsetail stems are hollow, and their cells accumulate high levels of silica. Ch a p te r 2 7 A cti ve L ec tu re Sl i d e 2 7 Fern Diversity -epiphytes live on other plants or outside 7  2/8/2025 Tree Fern and Aquatic Fern Ch a p te r 2 7 A cti ve L ec tu re Sl i d e 2 8 Azolla, an Aquatic Fern Azolla has been used as biofertilizer of rice paddies. The leaves of Azolla have a cavity where nitrogen- fixing bacteria reside, supporting rapid growth of the fern. This fern suppresses weed growth and provides nitrogen to the rice paddies. Fossil tree ferns from coal beds 8  2/8/2025 Angiosperms Me an num ber of s pe cie s per f os sil as sem blage Conif ers Cycads Gingkos Ferns and horset ai ls Lycophytes Extinct seed plant groups Extinct spore-dis persi ng plant groups Era of Co al Swamp Forests Plant Diversity A ngiosperms through Time Lycophyt es Conif ers Ferns a nd horsetai ls Cycad s Millions of ye ar s ago -angiosperms are flowering plants Seed Plants -grasses are a major group of angiosperms Seed plants do not require external water for reproduction. Seeds enhance dispersal, and the nutrient-rich tissue in the seed makes it more likely that the plant embryo will grow. Gymnosperm Phylogeny -conifers are most abundant 9  2/8/2025 Ch a p te r 2 7 A cti ve L ec tu re Sl i d e 3 3 Cycads Cycad fossils date back to 280 mya, were a do min ant type of pla nt in the Jurrasic, bu t only ~3 00 sp ecies re main to day. Ch a p te r 2 7 A cti ve L ec tu re Sl i d e 3 4 Ginkgos Gin kg os date back ~280 millio n yea rs, are re presented by a sing le surving species (Gin kg o b iloba) over the p ast 100 milli on ye ars. Ch a p te r 2 7 A cti ve L ec tu re Sl i d e 3 5 Conifers The conifers include pines, junipers, and redwoods. Most conifers are evergreen 10  2/8/2025 Conifers Conifers are one of the most econo mi ca lly impor tan t grou ps of p lants. Conifers Major source of timber, and pa per pul p. Ch a p te r 2 7 A cti ve L ec tu re Sl i d e 3 Conifer Distribution Conifers dominate the vast boreal forests They generally become more abundant as elevation increases and are common in dry areas 11  2/8/2025 Angiosperms Me an num ber of s pe cie s per f os sil as sem blage Conif ers Cycads Gingkos Ferns and horset ai ls Lycophytes Extinct seed plant groups Extinct spore-dis persi ng plant groups En d o f Cretace ous Plant Diversity A ngiosperms through Time Lycophyt es Conif ers Ferns a nd horsetai ls Cycad s Millions of ye ar s ago Angiosperm phylogeny An giosperms are pla nts th at have flowers Angiosperms – Insect pollination Insect pollin ators and flowers have co-evolved over the past 1 50 million years 12  2/8/2025 Ch a p te r 2 7 A cti ve L ec tu re Sl i d e 3 9 Factors Contributing to Angiosperm Diversity Pla nts th at attr act different pollin ato rs tend diverg e to form n ew species mo re readi ly wind-pol linated species. Flowerin g p lants with ani ma l p ollina tor s can rep roduce even if ind ivid uals are fa r a part, allo wi ng rare species to per sist a nd repro duce. Ch a p te r 2 7 A cti ve L ec tu re Sl i d e 4 4 Eudicots The eud ico ts first ap pear 12 5 mya. By 80-90 mya, most ang iosperms a re in thi s grou p. Eu dicots have two embryon ic cotyle dons (seed lea ve s). Eudicot structure Stem vascular bu ndles in a ring with vascu lar ca mb ium whi ch all ows gro wth in girth and ne w vascu lar tissue to b e gen erated throug hout the life of the pla nt Lea ve s are ne t-veine d 13  2/8/2025 -radicle is a root Eudicot structure Embryo with two co tyledo ns (seed leaves) Flower parts in multipl es of fou r o r five Lea ve s are ne t veined Stem vascular bu ndles in a ring Tap roots de ve lop fr om ra dicle Econo mica lly impor tan t dicots includ e ma ny impo rtan t crops: Po tatoes Cotton Pe ach es, So ybe ans Eg gplan ts nectarine s Cassa va (yuca) (aub ergin es) Pe as Tomatoes Mang os Oli ves Wate rmelons Su nflo we rs Coffee Swee t potatoes Pe anuts Strawbe rries Ap ples Chilis and pep pers Tobacco Cucumbers Tange rines and Tea ​ Gra pes clementine s, Sq uash and Ora nges Lettuce pump kin s Cabb ages and other Sp inach bra ssicas Ch a p te r 2 7 A cti ve L ec tu re Sl i d e 4 6 Monocots Mono cots h ave a sing le cotyle don and make up ~2 5% of a ll a ngio spe rms. 14  2/8/2025 Ch a p te r 2 7 A cti ve L ec tu re Sl i d e 4 7 Monocot Structure Mono cots d o n ot form a vascu lar cambium, in most mono cots the vascu lar bund les sca ttered throu ghou t th e cro ss sectio n of the ste m. Lea f veins a re also arran ged in par allel Monocot Structure Embryo with sing le co tyledo n Flower parts in multipl es of thre e Major lea f veins p arall el Stem vascular bu ndles scattered Roots ar e a dventitio us Monocots 25% o f ang iosperms, over 70% o f fo od we e at 15  2/8/2025 Econo mica lly impor tan t monocots in clu de: Gra sses: Coconuts Whea t, Rice and Dates Su garcane Maize acco unt for Ba nanas Maize (corn) 2/3 of all calor ies On ions Rice consumed by Pa lm oil Whea t peo ple​ Ga rlic Ba rley Ch a p te r 2 7 A cti ve L ec tu re Sl i d e 4 9 Expansion of Grasslands through Time 16  2/8/2025 Ch a p te r 2 7 A cti ve L ec tu re Sl i d e 5 0 When Grasslands Expanded Ch a p te r 2 7 A cti ve L ec tu re Sl i d e 5 5 Saving Genetic Diversity in Crop Plants Plant Phylogeny 17