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Meristem

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Meristems• Meristematic tissues are clumps of small

cells with dense cytoplasm and proportionately large nuclei.– Elongation of roots and shoots takes

place by repeated cell divisions and subsequent elongation by the apical meristem.

– In some species, lateral meristems produce an increase in girth.

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Meristems

• Apical meristems

– located at tip of stems and roots• Plant tissues that result from primary

growth are called primary tissues.

–make up primary plant body• root apical meristem protected by root

cap

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Apical Meristems• Give rise to three types of primary meristems

– protoderm - forms epidermis

– procambium - forms primary vascular tissue

– ground meristem - differentiates into ground tissue• intercalary meristems may arise in stem

internodes

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66

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Lateral Meristems• Most trees, shrubs, and some herbs have

active lateral meristems.– increases girth in nonwoody plants - secondary

growth

• Woody stems– cork cambium

• produces cork cells

– vascular cambium• produces secondary vascular tissue

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1010

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Jaringan Dewasa

• Jaringan sederhana disusun oleh sel2 yg homogen (1 tipe sel) co. parenkim, kolenkim, sklerenkim

• Jaringan kompleks bersifat heterogen, disusun oleh lebih dr 1 macam sel. Co. xilem, floem & epidermis.

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Parenkim

• Kebanyakan sel parenkim bbtk polihedron. Dpt mengandung kloroplas.

• Sel parenkim yg memanjang tdpt pd jar palisade daun. Sel parenkim btk bintang tdpt pd btg tumb dg rongga udara yg berkembang sempurna co. pd juncus.

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Parenkim…. Cont.

• Kebanyakan sel parenkim bddg sel tipis.• Sel parenkim dg fgs penyimpanan, misal pd

endosperm Coffea & Asparagus bddg sel tebal tempat terakumulasinya hemiselulosa sbg zat cad mkn.

• Pd tumb sukulen sel parenkim dpt menyimpan air dg vakuola besar.

• Sel parenkim idioblastik dpt mengandung berbagai zat co. enzim mirosin (cruciferae, capparidaceae), zat berminyak (lauraceae), zat berlendir (cactaceae, portulacaceae, malvaceae) & zat resin (meliaceae, rutaceae)

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Kolenkim• Bersama dg parenkim merupakan jaringan penunjang tumb

• Tdr dr sel hdp yg memanjang dfg ddg menebal tdk rata

• Bfgs sbg jar penunjang organ yg mulai tumbuh, herba & pd organ dewasa.

• Kolenkim muda bsft lentur & kolenkim dewasa kurang lentur, lbh keras & lbh rapuh (bsft plastik).

• Dpt berisi kloroplas & dpt pula berisi tanin.

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Kolenkim…. Cont.

Menurut penebalan ddg sel, ada 3 tipe utama kolenkim :• Kolenkim menyudut (angular), dg penebalan ddg sel tjd

pd sudut2 sel, co. pd tangkai daun vitis, begonia, coleus, cucurbita, btg Solanum tuberosum & Atropa belladona

• Kolenkim lamelar, penebalan tjd pd ddg tangensial. Co. pd korteks btg Sambucus nigra

• Kolenkim lakunar, penebalan di bag ddg sel yg menghadap ke ruang intraselular. Co. pd tangkai daun compositae, salvia, malva & asclepias.

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Kolenkim angularf

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Kolenkim lamelar

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Kolenkim lakunar

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Sklerenkim

• Sklerenkim adalah jaringan yg tjd dr sel2 dg penebalan ddg sekunder, yg berlignin atau tdk berlignin

• Bfgs utk menopang & pelindung, bsft elastik.

• Dibagi mjd serat & sklereid.• Serat adl sel pjgm sklereid

adl sel pdk.

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Sklerenkim…. Cont.

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Serat

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Sklereid