Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Plant Anatomy Spikelet Inflorescence Culm (stem) Node (joint) Internode Stolon Leaf Rhizome Plant TISSUES Dermal • epidermis (“skin” of plant) – single layer of tightly packed – cells that covers & protects plant Ground • bulk of plant tissue – photosynthetic mesophyll, – storage Vascular • transport system in – shoots & roots xylem & phloem – Plant CELL types in plant tissues Parenchyma • “typical” plant cells = least specialized – photosynthetic cells, storage cells – tissue of leaves, stem, fruit, storage roots – Collenchyma • unevenly thickened primary If walls I’d – only had triplets! support – Sclerenchyma • very thick, “woody” secondary walls support rigid cells that can’t elongate dead at functional maturity – – – – Parenchyma Parenchyma cells are unspecialized, thin, flexible & carry out many metabolic functions all other cell types in plants develop from parenchyma Fig. 38.12a Collenchyma Collenchyma cells have thicker primary walls & provide support help support without restraining growth remain alive in maturity the strings in celery stalks are collenchyma Fig. 38.12b Collenchyma Celery Sclerenchyma Thick, rigid cell wall • lignin (wood) – cannot elongate – mostly dead at maturity – Cells for support • xylem vessels – xylem tracheids – fibers – rope fibers • sclereids – nutshells • seed coats • grittiness in pears • Fig. 38.12c Schlerenchyma hau – used to make rope vessel elements Xylem vessel element Vascular tissue move water & minerals up from roots dead cells at functional maturity only cell walls remain need empty pipes to efficiently move H2O transpirational pull dead cells Aaaah… Structure–Function again! tracheids Fig. 4.9 Fig. 38.13b Fig. 38.13a Fig. 4.6 Phloem: food-conducting cells carry sugars & nutrients throughout plant sieve tube companion cell sieve plate plasmodesmata living cells Phloem: food-conducting cells sieve tube elements & companion cells Fig. 38.14a Fig. 38.14b Phloem Aaaah… Structure–Function again! Living cells at functional maturity • cell membrane, cytoplasm – control of diffusion • lose their nucleus, ribosomes & vacuole – more room for specialized transport of • liquid food (sucrose) Cells • sieve tubes – sieve plates — end walls — have pores to facilitate flow of • fluid between cells companion cells – nucleated cells connected to the sieve-tube • help sieve tubes • Fig. 38.15 Cross section of root Vascular bundle (Stele) = contains xylem and phloem Cortex Epidermis Root hairs Absorb water and minerals – • • • • Vascular tissue in roots: dicot phloem xylem Cross-section of a root Vascular tissue in roots: monocot xylem phloem Root Cross Section Vascular tissue in stems dicot trees & shrubs collect annual rings monocot grasses & lilies Cross-section: young dicot stem with ring of vascular bundles Fig. 38.25a Fig. 38.25b Monocot stem section showing scattered vascular bundles and enlargement of single vascular bundle (“monkey face”). Woody dicots Discrete vascular bundles replaced by • continuous rings of xylem Each ring is xylem produced during one • growing season Vascular cambium • Fig. 38.7a Fig. 38.7b Cross-section: woody stem showing 3 years of secondary growth. Note pith at center. Dark (reddish) ring is the bark containing a layer of living phloem and outer dead cork. Stems: Secondary growth •Vascular tissue, (xylem) makes up the bulk of the stem •Form tree rings Lilac leaf cross section Fig. 38.34 Fig. 38.8 Fig. 38.33