<<

to living tophyte features; formally include called are monophyletic During presence (discussed heat . cells, nutritional /

effecting DIVERSITY the attractant,

Sperm

62 A that Liverworts, The a egg shock paraphyletic fiavonoid in phase of cells the land the as the cell lacking recognized. CHAPTER the of the fertilization, acting the in dependence proteins. liverworts, various nonvascular enter early plants of name, of to Chapter , dominant, lineages OF the the chemical form true as the group, NONVASCULAR evolution land a ultrastructural placed life development These share homing vascular 4). 3 neck a and mosses, the of and diverged plants cycle. FIGURE diploid photosynthetic, land These EVOLUTION compounds, the defined homworts other are in many of device sporophyte tissue quotation of not the was plants It and cells lineages (2n) possible before is liverworts. and land 3.10 modifications by discussed archegonium thalloid hornworts. for likely and differ the . the or and the plants, (sterile “ I A. marks, in LAND persistent, may the serves upon absence ‘fl AND establishment “” apomorphies: that swimming having Antheridia. a from / in here. The proliferation vascular collectively nature, In “jacket” “Bryophytes” gametophytic the three as is of and the

DIVERSITY PLANTS sporophyte addition of the no the sperm a ancestral and vascular fertilize derived site similar layer) B. sperm. longer major, game— plants sperm free- Archegonia. of cells and the for be of to a OF neck the anchorage Thalloid dispersal; ponents , studies. : changes hot tissue; enings, Liverworts, been Many elaters, first meaning shaded the to ephemeral, (1) the of

LIVERWORTS B GREEN There The the Both one distinctive , monophyletic gametophyte habitats). land proposed, different liverworts, relationships this found areas another are elongate, As of in that are liverworts plants. as uniseriate, and apomorphies in AND and also is the carrying the moisture (although inside two hornworts oil they likely Among absorption. one relationships attached land traditionally thalloid and Today, (see nonsporogenous bodies groups mosses, LAND basic change recent of consist the to filamentous the later the of content. some the sporangium. the liverworts to and and that ancestral morphological land and of liverworts, PLANTS and discussion). Pores and , with shape of vascular apomorphies dries called mosses, (2) which are among are plants. a hornworts leafy nutritionally , specialized them Elaters adapted descendents in processes out, growing cells and are form, the is the Elaters the plants the mosses, seen (Figures the (Figures relatively Hepaticae, with move upper three a types function gametophyte to based elaters is of flattened in mostly spiral are periodically relatively structures that remain dependent in Figure of liverworts and surface lineages 3.11, hygroscopic, of on response minor some 3.11—3.13). twist function wall hornworts are in liverwort in cladistic mass 3.12K). unclear. 3.6. moist, one of out small, called thick of bears com upon have dry, the the are of of in of

to r

pore 4 gemmae (longitudinal-section) archegoniophore (longitudinal antheridiophore cup gemmae section) (n) propagules (n) thalloid liverwort F IGURE fertilization 3.11 (,, archegonium (0) II UN[T ••1• Liverwort (n) Ri I) 11 morphology EVOLUTION elater (longitudinal-section) archegoniophore and life AND cycle. capsule spore (n) (n) DIVERSITY dorsal dorsal 2 rows view (upper) leafy of OF liverwort sporophyte germinating PLANTS (2n) ventral ventral 1 view row (lower) leaves of

spore 63 to gametophyte plants living tophyte features; formally include called are monophyletic During presence (discussed heat tissue. cells, nutritional embryo/sporophyte

effecting DIVERSITY the attractant,

Sperm

62 A that Liverworts, The a egg shock paraphyletic fiavonoid in phase of cells the land the as the cell lacking recognized. CHAPTER the of the fertilization, acting the in dependence proteins. liverworts, various nonvascular enter hornworts early plants of name, of to Chapter mosses, dominant, lineages OF the the chemical form true as the group, NONVASCULAR evolution land a ultrastructural placed life development These share homing vascular 4). 3 neck a and mosses, the of and diverged plants cycle. FIGURE diploid photosynthetic, land These sperm EVOLUTION compounds, the defined homworts other archegonium are in many of device sporophyte tissue quotation of not the was plants It and cells lineages (2n) possible before is liverworts. and land 3.10 modifications by discussed archegonium thalloid hornworts. for likely and differ the zygote. the or and the plants, (sterile “ I A. marks, in LAND persistent, may the serves upon absence ‘fl AND establishment “bryophytes” apomorphies: that swimming having Antheridia. a from / in here. The proliferation vascular collectively nature, In “jacket” “Bryophytes” gametophytic the three as is of and the

DIVERSITY PLANTS sporophyte addition of the no the sperm a ancestral and vascular fertilize derived site similar layer) B. sperm. longer major, game— plants sperm free- Archegonia. of cells and the for be of to a OF neck the anchorage Thalloid dispersal; ponents rhizoids, studies. gametophytes: changes hot tissue; enings, Liverworts, been Many elaters, first meaning shaded the to ephemeral, (1) the of

LIVERWORTS B GREEN There The the Both one distinctive capsule, monophyletic gametophyte habitats). land proposed, different liverworts, relationships this found areas another are elongate, As of in that are liverworts plants. as uniseriate, and apomorphies in AND and also is the carrying the moisture (although inside two hornworts oil they likely Among absorption. one relationships attached land sporangium traditionally thalloid and Today, (see nonsporogenous bodies groups mosses, LAND basic change recent of consist the spores to filamentous the plant later the of content. some the sporangium. the liverworts to and and that ancestral morphological land and of liverworts, PLANTS and discussion). Pores and flora, with shape of vascular apomorphies dries called mosses, (2) which are among are plants. a hornworts leafy nutritionally thallus, specialized them Elaters adapted descendents in processes out, growing cells and are form, the is the Elaters the plants the mosses, seen (Figures the (Figures relatively Hepaticae, with move upper three a types function gametophyte to based elaters is of flattened in mostly spiral are periodically relatively structures that remain dependent in Figure of liverworts and surface lineages 3.11, hygroscopic, of on response minor some 3.11—3.13). twist function wall hornworts are in liverwort in cladistic mass 3.12K). unclear. 3.6. moist, one of out small, called thick of bears spore com upon have dry, the the are of of in of

to r

pore 4 gemmae (longitudinal-section) archegoniophore (longitudinal antheridiophore cup gemmae section) (n) propagules (n) thalloid liverwort F IGURE fertilization 3.11 antheridium (,, archegonium (0) II UN[T ••1• Liverwort (n) Ri I) 11 morphology EVOLUTION elater (longitudinal-section) archegoniophore and life AND cycle. capsule spore (n) (n) DIVERSITY dorsal dorsal 2 rows view leaves (upper) leafy of OF liverwort sporophyte germinating PLANTS (2n) ventral ventral 1 view row (lower) leaves of

spore 63 goniophores. H. Note sporogenous FIGURE

64 Archegoniophore, whitish CHAPTER 3.12 tissue, pores. E. Antheridiophore, Hepaticae C. showing longitudinal-section. Asterella, 3 — EVOLUTION spores Liverworts. a close-up. thalloid and elaters. A. liverwort F. 1. Conocephaluin AND Archegoniophore, Archegonium. L. Cross-section with DIVERSITY archegoniophores. sp., J. Capsule, a showing of thalloid thallus, OF capsules longitudinal-section, GREEN liverwort. showing D—L. . beneath rhizoids AND B. Marchantia, lobes. LAND and D. showing upper G. Thallus thallus Antheridiophore, PLANTS pores. sporogenous with with antheridiophores gemma longitudinal-section. tissue. cups and K. and Close-up, gemmae. arche

I reduced thallus FIGURE as the of 3.12B,L). be called ized tion with water genetic rows worts, axis most that 3.13). independently vascular worts ridiophores gametophyte. the gametangia ing into tually antheridium small, Leafy they As some After hornworts dispersed archegonia archegonia structures in the cyanobacteria. the bearing of row falls in differentiates gemmae Other have the nonphotosynthetic, vegetative leaves have of clone leaves diploid thalloid upper fertilization all plants liverworts 3.13 These (on stem some into of form of antheridia no bearing three leafy at of some (discussed the In called of similar. two the the the Hepaticae from arrows (Chapter (Figures regulating is (2n) (Figure the pores liverworts, species the some as stem (asexual) prostrate antheridiophore early gemma liverworts rows rows On into have parent. distance part sporophyte. archegoniophore, the gemma antheridia those (lower are The the underside) liverwort and a 3.11, 3.11, zygote diverging of 4). later), of — of function gametophytes diploid not upper guard and cup, Leafy leaves stalked, and thin such reproduction; leaves archegonia of side cups, away, 3.12B). are true 3.12). have short mosses the divides and the facing). leaves. surface This liverworts. cells. taxa as (2n) more of are swims in land stomata which are gemmae peltate leaves Marchantia, archegoniophores growing a leafy Sperm lived. effecting sporophyte embryo, gas These reduced (e.g., symbiotic Some larger mitotically erect, plant consisting that (discussed of In in contain liverworts when exchange are the structures: A. It (discussed most Marchantia), a released themselves structures develop liverworts, consists film into and lineages, Bazania modified with gametophytes which (Figures fertilization. relationship a are leafy propagules is the of droplet a of and relatively the later) special UNIT from evolved haploid water (Figure matures a anthe trilobata, on lower almost later), func liver even liver three 3.11, bear stem such may like the the of an or to II a At entirely phyte, worts otically, four leafy (under diverse The cular and one the (also ally rich which, better the sist 3.14). EVOLUTION , exchange, Carbon dark vapor from during mata. by-product, a side inhabit apomorphy size certain found in of valves. mosses, liverwort. termed reactions plants: the the Each completing In seal to suberin, by the the of facing two of forming dioxide of spores escape sun some changes the in a on right the a day stage, guard the The sporangium a of stomata) -containing number possession terms may or leaves, B. three the price . a photosynthetic of plants, with AND when exits are opening waxy, conditions), haploid Porella, from Musci, passing spores the stoma the cell cause in photosynthesis. of released major to turgor the of via internal but life both photosynthesis Stomata has the are DIVERSITY water-resistant loss be ecological may (Figure hornworts of a considerable (n) the are between sometimes through cycle. or leafy groups specialized . one paid pressure, photosynthesis stomates of spores by stoma. capsule by land and cells cells or water liverwort, function a In 3.14). for far splitting more of grow the on niches. most of them, Oxygen, (discussed (see Stomata entry within cells, nonvascular can on the (Figure OF the via (Figure water a takes substance, epidermal This stoma ridge-like Figure substrate, into stems. plants in increase capsule showing most stomata PLANTS the of of Mosses and material, and the regulation place; loss a also the a carbon 3.6). stoma diffuses 3.11, later) by-product new 3.7). Stomata water speciose stomata is guard capsule through functions cells divide third allow land or deposits is used may germinate Stomates thus, 3. decrease gameto and In simply which dioxide, (Figure uptake. 12F,J). row gener plants of to liver in water share cells, mei open con vas into heat

65 and sto gas the the on of to of is a goniophores. H. Note sporogenous FIGURE

64 Archegoniophore, whitish CHAPTER 3.12 tissue, pores. E. Antheridiophore, Hepaticae C. showing longitudinal-section. Asterella, 3 — EVOLUTION spores Liverworts. a close-up. thalloid and elaters. A. liverwort F. 1. Conocephaluin AND Archegoniophore, Archegonium. L. Cross-section with DIVERSITY archegoniophores. sp., J. Capsule, a showing of thalloid thallus, OF capsules longitudinal-section, GREEN liverwort. showing D—L. Marchantia. beneath rhizoids AND B. Marchantia, lobes. LAND and D. showing upper G. Thallus thallus Antheridiophore, PLANTS pores. sporogenous with with antheridiophores gemma longitudinal-section. tissue. cups and K. and Close-up, gemmae. arche

I reduced thallus FIGURE as the of 3.12B,L). be called ized tion with water genetic rows worts, axis most that 3.13). independently vascular worts ridiophores gametophyte. the gametangia ing into tually antheridium small, Leafy they As some After hornworts dispersed archegonia archegonia structures in the cyanobacteria. the bearing of row falls in differentiates gemmae Other have the nonphotosynthetic, vegetative leaves have of clone leaves diploid thalloid upper fertilization all plants liverworts 3.13 These (on stem some into of form of antheridia no bearing three leafy at of some (discussed the In called of similar. two the the the Hepaticae from arrows (Chapter (Figures regulating is (2n) (Figure the pores liverworts, species the some as stem (asexual) prostrate antheridiophore early gemma liverworts rows rows On into have parent. distance part sporophyte. archegoniophore, the gemma antheridia those (lower are The the underside) liverwort and a 3.11, 3.11, zygote diverging of 4). later), of — of function gametophytes diploid not upper guard and cup, Leafy leaves stalked, and thin such reproduction; leaves archegonia of side cups, away, 3.12B). are true 3.12). have short mosses the divides and the facing). leaves. surface This liverworts. cells. taxa as (2n) more of are swims in land stomata which are gemmae peltate leaves Marchantia, archegoniophores growing a leafy Sperm lived. effecting sporophyte embryo, gas These reduced (e.g., symbiotic Some larger mitotically erect, plant consisting that (discussed of In in contain liverworts when exchange are the structures: A. It (discussed most Marchantia), a released themselves structures develop liverworts, consists film into and lineages, Bazania modified with gametophytes which (Figures fertilization. relationship a are leafy propagules is the of droplet a of and relatively the later) special UNIT from evolved haploid water (Figure matures a anthe trilobata, on lower almost later), func liver even liver three 3.11, bear stem such may like the the of an or to II a At entirely phyte, worts otically, four leafy (under MOSS diverse The cular and one the (also ally rich which, better the sist 3.14). EVOLUTION chloroplasts photosynthesis, exchange, Carbon dark vapor from during mata. by-product, a side inhabit apomorphy size certain found in of valves. mosses, liverwort. termed reactions plants: the the Each completing In seal to suberin, by the the of facing two of forming dioxide of spores escape sun some changes the in a on right the a day stage, guard the The sporangium a of stomata) chloroplast-containing number possession terms may or leaves, B. three the price stoma. a photosynthetic of plants, with AND when exits are opening waxy, conditions), haploid Porella, from Musci, passing spores the stoma the cell cause in photosynthesis. of released major to turgor the of via internal but life both photosynthesis Stomata has the are DIVERSITY water-resistant loss be ecological may (Figure hornworts of a considerable (n) the are between sometimes through cycle. or leafy groups specialized leaf. one paid pressure, photosynthesis stomates of spores by stoma. capsule by land and cells cells or water liverwort, function a In 3.14). for far splitting more of grow the on niches. most of them, Oxygen, (discussed (see Stomata entry within cells, nonvascular can on the (Figure OF the via (Figure water a takes substance, epidermal This stoma ridge-like Figure substrate, into stems. plants in increase capsule showing most stomata PLANTS the of of Mosses and material, and the regulation place; loss a also the a carbon 3.6). stoma diffuses 3.11, later) by-product new 3.7). Stomata water speciose stomata is guard capsule through functions cells divide third allow land or deposits is used may germinate Stomates thus, 3. decrease gameto and In simply which dioxide, (Figure uptake. 12F,J). row gener plants of to liver in water share cells, mei open con vas into heat

65 and sto gas the the on of to of is a F

66 CHAPTER 3 EVOLUTION AND DIVERSITY OF GREEN AND LAND PLANTS UNIT II EVOLUTION AND DIVERSITY OF PLANTS 67

guardcells chloroplast of stomate operculum peristome teeth 0 / / 0

operculum/ II guardcells closed open of stomate

mature capsule FIGURE 3.14 Thestomate,an innovationformosses,hornworts,andvascularplants.A. Faceview,slightlyopen.B. Diagram,faceview, (sporangium) openand closed.C. Diagram,cross-section. germinating spore protonema which is essential for photosynthesis. However,in other plants, Antheridia and archegonia in mosses are usually produced .1/ such as tall , stomatal water loss may actually be adap at the apex of gametophytic stems (Figures 3.16, 3.17D—F). tive and functional, as a large quantity of water must flow After fertilization, the sporophyte grows upward (Figures antheridia through the leaves in order to supply sufficient quantities of 3.16, 3.17G) and often carries the apical portion of the origi sporophyte mineral nutrients absorbed via the . nal archegonium, which continues to grow. This apical arche (2n) A second apomorphy, possibly shared among mosses, gonial tissue, known as a calyptra (Figures 3.16, 3.17H), hornworts, and vascular plants, is an elongate, aerial sporo may function in protecting the young sporophyte apex. The phyte axis (Figure 3.6). The elongate, aerial sporophyte seen sporophyte generally develops a long stalk, known as a stipe, in mosses and hornworts may be a possible precursor to the at the apex of which is born the sporangiumor capsule (Figures evolution of the dominant, aerial sporophytic stem in vascu 3.16, 3.17G,H). The capsule of most mosses has a specialized lar plants (see Chapter 4). mechanism of dehiscence. At the time of spore release, a lid Mosses have a number of autapomorphies. First, some known as an operculum falls off the capsule apex, revealing stipe mosses have specialized conductive cells called hydroids, a of peristome teeth. The peristome teeth, like the which function in water conduction, and leptoids, which elaters of liverworts, are hygroscopic. As the capsule dries function in conduction. These cells resemble typical up, the peristome teeth retract, effecting release of the spores tracheary elements and phloem sieveelements (Chapter (Figures 3.16, 3.17H,I). costa archegonial 4), but lack the specializations of the latter cell types. They Under the right environmental conditions, moss spores neck likely evolved independently of (Figure 3.6), will germinate and begin to grow into a new gametophyte. although alternative hypotheses of “” relationships The initial development of the gametophyte results in the argue that hydroids and leptoids may represent intermediate formation of filamentous structure, known as a protonema structures in the evolution of true vascular tissue. Second, the (Figures 3.16, 3.17A). The protonema probably represents an spores of mosses have a thick outer layer called a perine ancestral vestige, resembling a filamentous green “alga.” layer (Figure 3.15), which maybe apomorphic for the mosses After a period of growth, the protonema grows into a paren alone (Figure 3.6) or possibly for the mosses and vascular chymatous gametophyte. plants combined. The perine layer may function in prevent ing excess desiccation and provide additional mechanical archegonia protection of the spore cytoplasm. As with liverworts and penile layer hornworts, a three-lined structure, called a trilete mark, develops on the spore wall; the trilete mark is the scar of 1/ attachment of the adjacent three spores of the four spores pro trilete mark duced at meiosis (Figure 3.15; see also Chapter 4). Thus, moss gametophytes are always leafy, with a variable number of leaf ranks or rows (Figures 3.16, 3.17B,C). The leaves of mosses are thought to have evolved independently from those in liverworts and, thus, constitute an apomorphy for the gametophyte mosses alone. Moss leaves are mostly quite small and thin, (n) but may have a central costa (Figure 3.17C), composed of FIGURE 3.15 Moss spore. Note protective perine layer and FIGURE 3.16 Mossmorphologyandlifecycle. conductive cells, which resembles a true vein. trilete mark. F

66 CHAPTER 3 EVOLUTION AND DIVERSITY OF GREEN AND LAND PLANTS UNIT II EVOLUTION AND DIVERSITY OF PLANTS 67

guardcells chloroplast of stomate operculum peristome teeth calyptra 0 / / 0

operculum/ II guardcells closed open of stomate

mature capsule FIGURE 3.14 Thestomate,an innovationformosses,hornworts,andvascularplants.A. Faceview,slightlyopen.B. Diagram,faceview, (sporangium) openand closed.C. Diagram,cross-section. germinating spore protonema which is essential for photosynthesis. However,in other plants, Antheridia and archegonia in mosses are usually produced .1/ such as tall trees, stomatal water loss may actually be adap at the apex of gametophytic stems (Figures 3.16, 3.17D—F). tive and functional, as a large quantity of water must flow After fertilization, the sporophyte grows upward (Figures antheridia through the leaves in order to supply sufficient quantities of 3.16, 3.17G) and often carries the apical portion of the origi sporophyte mineral nutrients absorbed via the roots. nal archegonium, which continues to grow. This apical arche (2n) A second apomorphy, possibly shared among mosses, gonial tissue, known as a calyptra (Figures 3.16, 3.17H), hornworts, and vascular plants, is an elongate, aerial sporo may function in protecting the young sporophyte apex. The phyte axis (Figure 3.6). The elongate, aerial sporophyte seen sporophyte generally develops a long stalk, known as a stipe, in mosses and hornworts may be a possible precursor to the at the apex of which is born the sporangiumor capsule (Figures evolution of the dominant, aerial sporophytic stem in vascu 3.16, 3.17G,H). The capsule of most mosses has a specialized lar plants (see Chapter 4). mechanism of dehiscence. At the time of spore release, a lid Mosses have a number of autapomorphies. First, some known as an operculum falls off the capsule apex, revealing stipe mosses have specialized conductive cells called hydroids, a whorl of peristome teeth. The peristome teeth, like the which function in water conduction, and leptoids, which elaters of liverworts, are hygroscopic. As the capsule dries function in sugar conduction. These cells resemble typical up, the peristome teeth retract, effecting release of the spores xylem tracheary elements and phloem sieveelements (Chapter (Figures 3.16, 3.17H,I). costa archegonial 4), but lack the specializations of the latter cell types. They Under the right environmental conditions, moss spores neck likely evolved independently of vascular tissue (Figure 3.6), will germinate and begin to grow into a new gametophyte. although alternative hypotheses of “bryophyte” relationships The initial development of the gametophyte results in the argue that hydroids and leptoids may represent intermediate formation of filamentous structure, known as a protonema structures in the evolution of true vascular tissue. Second, the (Figures 3.16, 3.17A). The protonema probably represents an spores of mosses have a thick outer layer called a perine ancestral vestige, resembling a filamentous green “alga.” layer (Figure 3.15), which maybe apomorphic for the mosses After a period of growth, the protonema grows into a paren alone (Figure 3.6) or possibly for the mosses and vascular chymatous gametophyte. plants combined. The perine layer may function in prevent ing excess desiccation and provide additional mechanical archegonia protection of the spore cytoplasm. As with liverworts and penile layer hornworts, a three-lined structure, called a trilete mark, develops on the spore wall; the trilete mark is the scar of 1/ attachment of the adjacent three spores of the four spores pro trilete mark duced at meiosis (Figure 3.15; see also Chapter 4). Thus, moss gametophytes are always leafy, with a variable number of leaf ranks or rows (Figures 3.16, 3.17B,C). The leaves of mosses are thought to have evolved independently from those in liverworts and, thus, constitute an apomorphy for the gametophyte mosses alone. Moss leaves are mostly quite small and thin, (n) but may have a central costa (Figure 3.17C), composed of FIGURE 3.15 Moss spore. Note protective perine layer and FIGURE 3.16 Mossmorphologyandlifecycle. conductive cells, which resembles a true vein. trilete mark. sp. showing ing (sterile 68 FIGURE gametophyte, capsules. layer) operculum, CHAPTER 3.17 H. and Moss face Mosses. internal one sporophyte view, 3 of sporogenous A. several showing EVOLUTION Protonema close-up, peristome antheridia tissue. of showing . F. teeth, AND Archegonia, at tips developmental and of DIVERSITY B. spores branches. Atrichum showing within E,F. series sp. stalk, OF sporangium. Mnium garnetophyte. (left egg GREEN to cell, sp. right). E. neck, AND Antheridia, C. I. Mnium Mnium, and

I LAND neck ‘ leaf, --I longitudinal-section, capsule canal showing PLANTS cells. (sporangium) C. median showing costa. longitudinal-section, D. of external Polytrichum moss, show wall

I I

r retention, hyaline gametophytes worts dently), phyletic Sphagnum thickenings clear tion with Homworts gametophyte important Sphagnum mixtures. Sphagnum genus few llve The chiorophyllous leaves environment land a all HORNWORTS FIGURE symbiotic One land inside with homworts, thafloid plants. some hyaline Sphagnum, may economically cells. of plants but group the 3.18 Sphagnum making fuel cavities species Peat and differ relationship grows remarkable Hornworts (Figure not also C. roots liverworts by morphology except and comprising cells, source Leaf is formally Sphagnum, in making cells, have from mined is of or a of having in it mosses. close-up, fungus, 3.18). liverworts vascular peat having quite the fossilized important wet are in with are a liverworts, which as properties known for thallus. parts moss, the stomates, symbiotic unusual a bogs The and valuable similar or well Interestingly, cyanobacteria similar third use showing characteristic plants. peat surrounding of (Figure pores are form moss as containing in This and (probably and the extant moss. Anthocerotae, to however, potting in to found a of horticulturally world. association chiorophyllous chemically the relationship presumed of worth the a having 3.6). partially water lineage the A. network, thalloid hornworts mycorrhizal (blue-greens), in mixtures All numerous Clonal water pores evolving hyaline mentioning in similar two absorption homworts of lacking apomorphy decomposed between liverworts modifies is are acidic. population. nonvascular and cell and cells, in found cells and and indepen habitats. a species. associa UNIT potting helical mono types: which pores, large, is as liver hyaline have give The and in the the its an of in a B. II Individual cells, unique region This tophyte), liverworts sporophyte gametophytic the gametophytic 3.19A,B). similar In phyte sporangium amelia (potentially similar scopic of morphy 3.19D,E). surface addition, sisting sister EVOLUTION The Some fact, pores, cohering, sporophyte, of to region independent basic leaf cells, function to the of in and of hornworts shared compared the and recent the constituting that sterile This (Figure being and Other actively sporophyte at (just the vascular spiral continuous) called life foot center, nonsporogenous, which is tissue tissue, of between molecular mosses. AND production to cylindrical above known surrounded cycle (nonspore-producing) mosses wall cylindrical, of apomorphies is the 3.19E). pseudo-elaters to of showing photosynthetic dividing are (Figure plants hornworts its thickenings the elaters of DIVERSITY incipient the an of them as The nonhomologous growth, surface some in gametophyte point analyses apomorphy hornworts of The (Figure the the sporophyte being 3.19C). of is cells sporophyte by and specialized hornworts specialized elongate, is the foot, of liverworts. include of intercalary rhizoids. somewhat via somewhat a aerial attachment hyaline and photosynthetic 3.6). place (Figure sporophyte. near OF The protective a is is relatively for for tissue basal, has PLANTS One similar embedded a and is chlorophyllous the generally the cells. with proximal of structures Thus, long the unique 3.19F), capable meristern lobed indeterminate lobed elongate, possible hornworts hornworts base to called intercalary but hornworts. The periods. long-lived. to the collar (Figure and (Figure that have central groups hygro of of end within game sporo in a apo is per col but and the 69 the the of of of In as is a a sp. showing ing (sterile 68 FIGURE gametophyte, capsules. layer) operculum, CHAPTER 3.17 H. and Moss face Mosses. internal one sporophyte view, 3 of sporogenous A. several showing EVOLUTION Protonema close-up, peristome antheridia tissue. of showing Sphagnum. F. teeth, AND Archegonia, at tips developmental and of DIVERSITY B. spores branches. Atrichum showing within E,F. series sp. stalk, OF sporangium. Mnium garnetophyte. (left egg GREEN to cell, sp. right). E. neck, AND Antheridia, C. I. Mnium Mnium, and

I LAND neck ‘ leaf, --I longitudinal-section, capsule canal showing PLANTS cells. (sporangium) C. median Sporophytes showing costa. longitudinal-section, D. of external Polytrichum moss, show wall

I I

r retention, hyaline gametophytes worts dently), phyletic Sphagnum thickenings clear tion with Homworts gametophyte important Sphagnum mixtures. Sphagnum genus few llve The chiorophyllous leaves environment land a all HORNWORTS FIGURE symbiotic One land inside with homworts, thafloid plants. some hyaline Sphagnum, may economically cells. of plants but group the 3.18 Sphagnum making fuel cavities species Peat and differ relationship grows remarkable Hornworts (Figure not also C. roots liverworts by morphology except and comprising cells, source Leaf is formally Sphagnum, in making cells, have from mined is of or a of having in it mosses. close-up, fungus, 3.18). liverworts vascular peat having quite the fossilized important wet are in with are a liverworts, which as properties known for thallus. parts moss, the stomates, symbiotic unusual a bogs The and valuable similar or well Interestingly, cyanobacteria similar third use showing characteristic plants. peat surrounding of (Figure pores are form moss as containing in This and (probably and the extant moss. Anthocerotae, to however, potting in to found a of horticulturally world. association chiorophyllous chemically the relationship presumed of worth the a having 3.6). partially water lineage the A. network, thalloid hornworts mycorrhizal (blue-greens), in mixtures All numerous Clonal water pores evolving hyaline mentioning in similar two absorption homworts of lacking apomorphy decomposed between liverworts modifies is are acidic. population. nonvascular and cell and cells, in found cells and and indepen habitats. a species. associa UNIT potting helical mono types: which pores, large, is as liver hyaline have give The and in the the its an of in a B. II Individual cells, unique region meristem This tophyte), liverworts sporophyte gametophytic the gametophytic 3.19A,B). similar In phyte sporangium amelia column (potentially similar scopic of morphy 3.19D,E). surface addition, sisting sister EVOLUTION The Some fact, pores, cohering, sporophyte, of to region independent basic leaf cells, function to the of in and of hornworts shared compared the and recent the constituting that sterile This (Figure being and Other actively sporophyte at (just the vascular spiral continuous) called life foot center, nonsporogenous, which is tissue tissue, of between molecular mosses. AND production to cylindrical above known surrounded cycle (nonspore-producing) mosses wall cylindrical, of apomorphies is the 3.19E). pseudo-elaters to of showing photosynthetic dividing are (Figure plants hornworts its thickenings the elaters of DIVERSITY incipient the an of them as The nonhomologous growth, surface some in gametophyte point analyses apomorphy hornworts of The (Figure the the sporophyte being 3.19C). of is cells sporophyte by and specialized hornworts specialized elongate, is the foot, of liverworts. include of intercalary rhizoids. somewhat via somewhat a aerial attachment hyaline and photosynthetic 3.6). place (Figure sporophyte. near OF The protective a is is relatively for for tissue basal, has PLANTS One similar embedded a and is chlorophyllous the generally the cells. with proximal of structures Thus, long the unique 3.19F), capable meristern lobed indeterminate lobed elongate, possible hornworts hornworts base to called intercalary but hornworts. The periods. long-lived. to the collar hornwort (Figure and (Figure that have central groups hygro of of end within game sporo in a apo is per col but and the 69 the the of of of In as is a a 70 CHAPTER 3 EVOLUTION AND DIVERSITY OF GREEN AND LAND PLANTS UNIT II EVOLUTION AND DIVERSITY OF PLANTS 71

REVIEW Q..VESTIONS

GREEN PLANTS 1. What are two formal names for the green plants? 2. What are apomorphies for the green plants? 3. The bulk of the primarycellwall of greenplantsis composedof what substance?(Givethe commonname and chemicalname.) 4. Is the synthesized inside or outside the plasma membrane? 5. What are the unique features of green plant chloroplasts? 6. How are chloroplasts thought to have originated (i.e., by what evolutionary process)? 7. What is a haplontic life cycle? Draw and label. 8. What is oogamy? 9. Describe and give the function of plasmodesmata.

I LAND PLANTS 10. What is the formal name for the land plants? 11. Name the major apomorphies of the land plants. 12. Draw and label the basic haplodiplontic life cycle (alternation of generations) of all land plants, illustrating all structures, processes, and levels. 13. What is an embryo? 14. What is a sporangium? 15. Name the possible adaptive features of the sporophyte. 16. What are cutin and cuticle and what are their adaptive significance? 17. Define apical growth and parenchyma. 18. In land plants what is the name of the pectic-rich layer between adjacent cell walls that functions to bind them together? 19. What is an antheridium? Draw and label the parts. 20. What is an archegonium? Draw and label the parts.

LIVERWORTS, MOSSES, AND HORNWORTS 21. Draw a phylogenetic denoting relationships of the liverworts, mosses, hornworts, and vascular plants. 22. What is the formal name of the liverworts? 23. Name two apomorphies of the liverworts. 24. What is the function of elaters? 25. What are the two major morphological forms of liverworts? Which is likely ancestral? 26. What are gemmae and gemma cups? 27. Describe the morphology of the leaves of leafy liverworts. 28. What is an antheridiophore? An archegoniophore? FIGURE 3.19 Homworts,Anthocerossp.A. Populationof gametophyteswith attachedsporophytes.B. Gametophytewith attached,cylin 29. Describe the structural makeup and function of a stomate. dricalsporophyte.C. Close-upof sporophytebase,showingensheathingcollarof gametophytictissuesurroundingintercalarymeristemof 30. What land plant groups possess stomates? sporophyte.D. Wholemountof sporophytebase,showingfoot embededwithingametophyte.E. Longitudinal-sectionof sporophytebase. 31. What possible apomorphies may be shared by the mosses, hornworts, and vascular plants? Note basal foot and actively dividing cells of intercalary meristem at sporophyte base. F. Sporophyte longitudinal-section, showing columella, 32. What is the formal name of the mosses? spores,andpseudo-elaters. 33. Name major apomorphies shared by the mosses alone. 34. What is a calyptra, stipe, operculum, peristome tooth? sporophytes may represent a transition to the very dominant, giomorphaorPan-Tracheophyta;seeChapter4), suchasthegenus 35. What is the scientific name of peat moss? long-lived sporophytes of vascular plants (Chapter 4). (not illustrated),were similarto hornworts,liver 36. What feature of the leaf anatomy of peat moss enables the leaves to absorb and retain water? worts, and mosses in lacking vasculartissue. However,they are 37. How is peat moss of economic importance? POLYSPOBANGIOPHYTES/PAN-TRACHEOPHYTA differentfrom “bryophytes,”and linkedto the vascularplants, in 38. What is the formal name of hornworts? This group is inclusive of a few,basal fossil taxa plus all of the havingbranchedstemswithmultiplesporangia(Figure3.6).Thus, 39. Describe the major features of hornworts, citing how they differ from the liverworts and mosses. true vascular plants, or tracheophytes (Chapter 4). The the polysporangiophytesincludetaxa that were transitionalto the 40. What is the function of pseudo-elaters, and how do they differ structurally from the elaters of liverworts? first-evolving polysporangiophytes (formally the Polysporan- tracheophytes. 41. What feature of the sporophyte might unite the hornworts with the vascular plants? 42. What apomorphy links the Pan-Tracheophyta/polysporangiophytes with the vascular plants?