Venation (Damarlanma) = yaprakta venlerin dağılımı Netted-venation = bir veya birkaç dominant midvein vardır aralarda daha ince ağsı damarlar bulunur (dicotlar) –Pinnately-veined leaves = midrib denen ana damar, burdan orjinlenen secondary veinler –Palmately-veined leaves = veinler blade tabanından ayrılır (maple). Paralel venation = monocots (grasses, cereal grains); venler birbirine paralel Dikotomus venation = midrib veya büyük venler yok; benzer ebatta cok sayıda ven çatal oluşturarak tabandan iki farklı yöne gider, fan şekilli yaprak
3. Detachment –abscission zone: Parenkima hücreleri bazi cell wall enzimleri salgılar (glucanases and pectinases); self digest Hücler su alır şişer
TRANSPIRATION Plants must supply water to all their tissues. It moves from the roots up the stem to the leaves by capillary action. The evaporation of water vapor from plant surfaces is called transpiration. Stoma neden var
Stomanın açılıp kapanması transpirasyonu düzenler Az Su, düşük sıcaklık, ışık ; kapalı gündüz açık gece kapalı guard cells
GUARD CELLS AND PLANT HOMEOSTASIS kidney-shaped with thick inner walls and thin outer walls. When they become full of water (turgid) the unevenness of the walls causes them to bow outward and the stomate opens. When they lose water they become less turgid and the stomate closes. Guard cells gain and lose water by osmosis.
Stomatal guard cells Environmental factors are sensed by guard cells –Light intensity, temperature, relative humidity, intercellular CO 2 concentration Integrated into well defined responses –Ion uptake in guard cell –Biosynthesis of organic molecules in guard cells This alters the water potential in the guard cells Water enders them Swell up 40-100%
Plants and water Bitkiler dehidrasyondan uzak durmak ister water conservation X CO 2 assimilation –Bazı yapılar su dengesinde önemli –1: iyi gelişmiş root– to get water from soil –2: suya direnç götermeyen taşıma– xylem –3: leaf cuticle – reduces evaporation –4: stomata – controls water loss and CO 2 uptake –5: guard cells – control stomata.
Habitatlara göre bitkiler Mesophytes : plants adapted to a habitat with adequate water Xerophytes : plants adapted to a dry habitat Halophytes : plants adapted to a salty habitat Hydrophytes : plants adapted to a freshwater habitat
Xerophytes Sunken stoma Hair, air current Waxy cuticle waterproof Rolled leaf Daha az stoma Küçük yaprak İyi kök sistemi
AdaptationHow it worksExample thick cuticle stops uncontrolled evaporation through leaf cells small leaf surface area less surface area for evaporation conifer needles, cactus spines low stomata densitysmaller surface area for diffusion sunken stomatamaintains humid air around stomata marram grass, cacti stomatal hairs (trichores) maintains humid air around stomata marram grass, couch grass rolled leavesmaintains humid air around stomata marram grass, extensive rootsmaximise water uptakecacti
Left and right Epidermis of the cactus Rhipsalis dissimilis. Left: View of the epidermis surface. The crater-shaped depressions with a guard cell each at their base can be seen. Right: X-section through the epidermis & underlying tissues. The guard cells are countersunk, the cuticle is thickened. These are classic xerophyte adaptations.
Transverse Section Through Leaf of Xerophytic Plant
Specialized or Modified Leaves In pine trees, the leaves are adapted to living in a dry environment too. Water is locked up as ice during significant portions of the year and therefore not available to the plant; pine leaves possess –sunken stomata, –thick cuticles –needle-like leaves –hypodermis, which is an extra cells just underneath the epidermis –