Plant Physiology Unit 3

Life Cycle of Plants Annual – a plant that completes its life cycle in one year Biennial – a plant that completes its life cycle in two years (usually grows in the first year and flowers in the second year) Perennial – a plant that lives more than two years (some will grow and bloom in the first year)

Leaf Retention of a Plant Deciduous – plants that lose their leaves during the dormant season Evergreen – plants that retain their leaves and remain green year round

Moisture in Plants Turgid – a plant that is swollen or filled with moisture Wilted – a plant that is limp because it does not have enough moisture

Plant Growth Dormant – a stage when a plant rests or grows very little Plants generally go dormant in response to adverse conditions such as extreme heat or cold Botany – the part of biology that deals with plants

Season Crop Type Cool season plants – relish cool temperatures, growing best in spring or fall (ex – pansy) Warm season plants – grow best in warm temperatures, growing best in the summer and every fall (ex – zinnia, marigold, vinca) https://youtu.be/Jns7e0fm9i0 https://youtu.be/E36JdAYb1zw https://youtu.be/LlFl363EYac

https://youtu.be/p3St51F4kE8 Plant Anatomy https://youtu.be/p3St51F4kE8

Leaves External Parts Petiole – the lead stalk or part that connects the leaf to the stem Midrib – the large center vein Blade – the large, flat part of the leaf Veins – the structural framework of the leaf Margin – the edge of the leaf Apex – the leaf tip

Leaves

Leaves Internal Parts Upper and lower epidermis – the skin of the leaf that prevents the loss of too much moisture Stomates – the small openings under the leaf for breathing or transpiration Guard cells – surround the stomates and regulate the open and close of the stomates Chloroplasts – small green particles that contain chlorophyll, give leaves their green color, and are necessary for photosynthesis

Leaves

Leaves Functions of the leaf Photosynthesis – process by which plants capture sunlight and use it to convert carbon dioxide and water into food (sugar) Respiration – converts sugars and starches into energy Transpiration – the release of water vapor from the leaves of plants and it helps cool the plants

Leaves https://youtu.be/D1Ymc311XS8

Leaves Leaves additional Sessile describes leaves without a petiole (ex – zinnia) Bracts are modified leaves (ex – poinsettia) Needles and scales are modified leaves (ex – pine tree) Glabrous leaves or stems have a smooth non-hairy feel (ex – southern magnolia) Pubescent leaves or stems have a hairy feel (ex – African violet)

Stems External parts Lenticels - breathing pores found on stems and branches Bud scale scars - indicate where terminal buds have been located Leaf scars - indicate where leaves were attached Terminal bud - a bud on end of stem Axillary bud - the bud located at the axil of the leaf Lateral buds - buds on side of stem

Stems Internal parts Xylem – the tissue that transports water and nutrients up from the roots to the stem and leaves Phloem – the tissue that transports food down from leaves to the roots Cambium – a thin, green, actively growing tissue located between the bark and wood and produces all new stem cells Bark – old inactive phloem Heartwood – old inactive xylem Sapwood – new active xylem

Stems Phloem Phloem Xylem

Stem Bark Cambium Sapwood Heartwood

Stems Cotyledons Monocots – plant systems that have vascular bundles which contain xylem and phloem; they produce one seed leaf (ex – grass & corn) Dicots – plant stems that have a phloem layer and xylem layer separated by cambium; they produce two seed leaves (ex – trees & vegetables)

Stems Xylem Cambium Phloem Dicot Monocot

Stems Functions of the stem Translocation – the movement of water and minerals through the plants; the phloem moves food down from the leaves to the roots The xylem moves water and nutrients up from the roots to the leaves

Roots External parts Root cap - located at the tip of the root and is where new cells are produced Root hairs – absorb moisture (water) and minerals

Roots Internal parts Phloem – the outer layer of the root and carries food down the root Xylem – the inner layer and carries water and minerals up to the stem

Roots

Roots Types of roots Fibrous roots have many branched shallow roots; they are easy to transplant Tap roots are long roots with few branched ones; they are more difficult to transplant

Roots Functions of roots Anchorage Absorption Asexual Reproduction Storage

Flowers (develop into seeds & fruits) External parts Sepals – the green parts of the flower that cover and protect the flower bud before it opens Petals – leaves that are modified to attract insects for flower pollination

Flowers (develop into seeds & fruit) Internal parts Stamens – male flower parts Anther – a sac like structure that contains pollen and male sex cells Filament – a short stalk that holds up the anther

Flowers (develop into seeds & fruit) Internal parts Pistil – female part of the flower Stigma – sticky pat on top of the style where insects leave pollen Style – hold up the stigma and connects it to the ovary Ovary – if fertilized, becomes a fruit Ovules – the eggs or female sex cells that become seeds if fertilized

Flowers

Flowers

Flowers (develop into seeds & fruit) Functions of the flower It attracts insects for pollination It produces seeds for sexual reproduction It produces fruit to nourish and protect the seed https://youtu.be/djPVgip_bdU

Flowers Additional flower and fruit information Complete flowers have both male and female parts Incomplete flowers have only male or female parts

Flowers

Flowers Additional flower and fruit information Fertilization – when pollen travels down the style, joining the sperm and the ovule Pollination – the transfer of pollen from the anther to the stigma Cross-pollination – the transfer of pollen from the stamen to the stigma of one flower to a flower on another plant Self-pollination – the transfer of the pollen to the stigma of a flower on the same plant

Flowers Additional flower and fruit information Corolla – all auxiliary parts of the flower not including reproductive organs; the collective term for all petals of a flower Calyx – the external usually green or leafy part of a flower; also the collective term for all sepals of a flower Receptacle – the enlarged tip of a stem on which a flower is born

Flowers Additional flower and fruit information The fruit serves as protection for the seed The function of the fruit is to help with seed dispersal The juvenile stage is when a plant first begins growing from a seed