HORT 101 Leaves and Stems Notes
HORT 101 Leaves and Stems Notes HORT 101
Popular in Fundamentals of Horticulture
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This 4 page One Day of Notes was uploaded by Mariah Rodriguez on Friday January 30, 2015. The One Day of Notes belongs to HORT 101 at Purdue University taught by Michael Dana in Spring2015. Since its upload, it has received 87 views. For similar materials see Fundamentals of Horticulture in Agriculture and Forestry at Purdue University.
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Date Created: 01/30/15
Tuesday January 27 2015 HORT101 Leaves and Stems Notes Leafs required features for a leaf exposed to sunlight large surface area able to exchange gases 002 in and 02 out import mineral nutrients and water export fixed carbon to quotSINKSquot control water loss resist biotic and abiotic stresses anatomical features of a leaf blade A ical leaf typ max the surface area while minimize the volume stem axilwith reduce distance that gases have to get axillary bud through the leaf leaf structure will vary and adapt to diverse conditions and environments internode node l Ieaf Ieaf w oepidermis outer later of the cells has a number of different cell types covered in a waxy cuticle the wax is secreted from epidermal cells makes the leaf impermeable to waterhelps to retain water inside the leaf cells in the epidermis epidermal cells most abundant lacks chloroplasts guard cells form stomata stomata pores in the epidermis that lead to intercellular spaces within the leaf found on both upperadaxial and lowerabaxial parts of the leaf Tuesday January 27 2015 important for photosynthesisallow gas exchange 002 in and 02 out no 002no photo the stomata have to be open for photosynthesis water is lost through this stomata cant be open all the time because interior of leaf is moist and when it is open large amount of water evaporates from the leaf like when you leave your mouth open plants can control water loss because stomata opens and closes guard cells have thickened inner cell walls when guard cells are turgid stomata are open when water comes out of guard cells stomata closes when is stomata open and closed stomata open when Calvin cycle is operating closed at night most of the time conserves water theres no need for 002 exchange plant will stop fixing carbon to retain water 0AM plants plants that evolve to conserve water trichomes leaf hairs cell protrusions from epidermis have protective functions stinging globular trichomes release compounds that are toxic to insects secretory hairs allow plants to secrete compounds Mesophyll Tissue spongy parenchyma cells randomly arranges airspaces allow diffusion of gases few chloroplasts designed for interception of light energy fixing 002 exchange of gases Vascular TissueVeins Tuesday January 27 2015 transport material to and from leaf import of water and nutrients into leaf export of photosynthate from leaf vascular bundles organized as bundles containing xylem and phloem Xylem distributions of water and minerals transported from root Cells are dead Phloem quotactivequot transportenergy required of fixed carbon compounds from the leaf to rest of plant Cells are alive Sclerenchyma thickened fibers that provide structural strength to the leaf leaf morphology varies between species simple leaf single leaf blade at each node compound leaves multiple leaflets describe leaves by shapemargins stem attachment Tendrils modified leaves that allow plants to vine spines and thorns protect some plants from predation some plants have other functions fly trap to capture insects an important source of nutrients Stems vary in size vary in strength soft fleshy stems of aquatic plants to tree trunks vary in longevity annual stems to long lived stems functions of plant stems A quottypicalquot stem apical meristem leaf primordium stem axil with axillary bud internode node Tuesday January 27 2015 provide a structure to support other organs leaves flowers fruit transport of material throughout the plant waters and minerals from root to shoot from souroesleaves to sinks roots fruits flowers Meristems Small composed of actively dividing undifferentiated ces mitosis source of new cells for the growth of any plant tissue found at various places throughout plant Apical Meristems lie near the tipsapices of shoots and roots shoot apical meristems produce stem and leaf tissues vegetative structures can switch to a floral meristem and produce flowers switch triggered by day length temp etc cells in a meristem small thin cell walls contain little or no vacuole