Ch26

PLANT KINGDOM SEEDLESS PLANTS I. Origin. Earth Chronology: 4.6 billion years ago: the earth formed. 4-3.8 billion years ago: life originated. 3.8 billion years ago: prokaryote anaerobes, heterotrophs. 3.5 billion billion years years ago: oldest known fossils: mirofossils and stromatolites! stromatolites! photosynthesis. photosynthesis. ".5 billion years ago: photosynthesis photosynthesis established, o#ygen a$m$lated. %.5 billion years ago: first e$karyotes. &'' million years ago soft-bodies m$ltiell$lar m$ltiell$lar life. 54' million years ago hard-bodied m$ltiell$lar m$ltiell$lar life. (he oloni)ation of land by plants probably o$rred between 4%5 and 44' million years ago at the end of  the *il$rian. +n a relatiely short time of abo$t 5' million years, plant diersified ab$ndantly and oloni)ed many land areas. and plants probably are probably deried from a gro$p of green algae alled harophytes. and plants share with the green algae the following traits: %. ". 3. 4. 5.

Chlorophy Chlorophyll ll a and b, #anthophy #anthophylls lls yellow yellow arotenoids/ arotenoids/ and arotenes arotenes orange orange arotenoi arotenoids/. ds/. *tore *tore arbo arbohy hydra drates tes in in the form form of of starh starh.. Cell Cell wall wall made made most mostly ly of of ell$ ell$los lose. e. 0etail 0etailss of the the formati formation on of the the ell ell plate plate.. 012 and 12 se$enes se$enes s$ppo s$pport rt their their lose relation relation to the the harophy harophytes. tes.

I. CHARACTERISTICS %. $ltiell$ $ltiell$lar lar e$karyo e$karyotes tes that that are photosy photosynthet ntheti i a$totroph a$totrophs. s. • • •

Chloroplasts Chlorophyll a and b. 2essory pigments: arotenes and #anthophylls #anthophylls

". Cell wall made of ell$l ell$lose, ose, a gl$os gl$osee polym polymer. er. 3. *tore *tore food food in plas plastid tidss in the the form form of star starh. h. 4. 2ltern 2lternati ation on of genera generatio tions. ns. 5. ormati ormation on of ell ell plate plate d$ring d$ring ytok ytokine inesis sis..

Eol$tionary trend towards a larger sporophyte generation and a red$ed gametophyte generation. 7ryophytes, *eedless as$lar 9lants, ymnosperms, 2ngiosperms.

II. ADAPTATIONS ADAPTATIONS TO A TERRESTRIAL TERRESTRI AL ENVIRONMENT. ENVIRONME NT.

%. ;a#y cuticle to protet against desiation. ". Stomata for gas e#hange and ontrol of transpiration. 3. Multicellular gametangia made of a layer of sterile ells to protet gametes: • •

2ntheridia prod$e sperms. 2rhegonia prod$e eggs.

4. 2fter 2fter fertil fertili)a i)atio tion, n, the egg egg deelop deelopss into into a multicellular emr!o within the arhegoni$m. ar hegoni$m. 5. Cell Cell wal walll on onta tain inss lignin, a polymer, to strengthen and s$pport $pright str$t$res. 6. (ran (ransp spor ortt syst system em or "a#cular ti##ue: • •

9hloem for the transport of dissoled arbohydrates. ornwort gametophytes are all thalloid. (he sporophyte is horn-shaped and parasiti on the gametophyte. gametophyte. >ornworts hae a single large hloroplast in their ells. IV. EVOL(TION.

(he eol$tionary origin of the bryophytes is obs$re. (hey do not seem to be in diret line with the as$lar plants and might hae eoled from a gro$p o green algae. 2lternatiely, 2lternatiely, they may hae eoled from early as$lar plants by beoming simpler in their anatomy by losing their as$lar tiss$e.

$ERNS AND $ERN ALLIES.

2lso known as pteridophytes, they first appeared abo$t 4'' million years ago. I. CHARACTERISTICS CHARACTERISTICS

%. erns and fern fern allies hae hae as$lar as$lar tiss$e tiss$e made of #ylem #ylem and phloem! phloem! they posses tr$e tr$e roots, roots, stems rhi)omes/ and leaes megaphy  megaphylls/. lls/. ". (he sporo sporophy phyte te is the domi dominan nantt generat generation ion.. 3. ametophyte prothall$s/ and sporophyte sporophyte generations are photosyntheti photosyntheti and independent independent of one one another. 4. 2ll speies speies need need water for for reprod$ti reprod$tion! on! the the sperm m$st m$st swim from from the antherid antheridi$m i$m to the arhegoni$m. 5.

7ran 7ranh hin ing g is di diho hoto tomo mo$s $s..

(he Telome T)eor! attempts to e#plain the prod$tion of megaphylls megaphylls in as$lar plants: eoled from a  branh system. +n ontrast, mirophylls are onsidered to hae eoled from small pro?etions of the stem. (hey are sale-like pro?etion with a single ein. II. $ERNS

2bo$t %4,''' e#tant speies. any speies are e#tint. *porangia are often prod$ed in l$sters alled sori sing. sor$s/. erns are al$able ornamentals. 2)olla, an a$ati fern, is an important fertili)er in the $ltiation of rie. •

assoiated to 2nabaena, a nitrogen fi#ing yanobateria.

III. $ERN ALLIES ')i#*+ern sporophytes onsist onsist of a rhi)ome with rhi)oids, and $pright branhes! they lak tr$e leaes and roots. Hor#etail# hae tr$e roots, stems and leaes. (he stems are hollow. (heir epidermal ells are impregnated with silia.

>orsetails were the dominant plants abo$t 3'' million years. (hey were among the main ontrib$tors to the formation of oal, gas and petrole$m fossil f$els/. (he sporophytes of clumo##e# onsist of tr$e roots, stems and leaes mirophylls/. *ome l$bmosses *elaginella/ are )etero#,orou#! yopodi$m is )omo#,orou#.

•

Homo#,or!: prod$tion of one kind of spores.

•

Hetero#,or!: prod$tion of two kinds of spores.

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>aploid mega#,ore#  deelop into a female gametophyte. >aploid micro#,ore#  deelop into a male gametophyte. gametophyte.

(he sporangia of horsetails and l$bmosses are arranged into an elongated onial str$t$re alled strobil$s pl. strobili/. *eedless as$lar plants arose abo$t 4"' million years ago in the mid-*il$rian. Coal formed from the remains of horsetails, ferns and other seedless plants that lied d$ring the Carbonifero$s, abo$t 3'' million years ago.

(he sporangia of horsetails and l$bmosses are arranged into an elongated onial str$t$re alled strobil$s pl. strobili/.