The Plant Kingdom Ch 13A and 14.6

Botany- the study of plants Human population is expected to reach 9 billion in 2050. We have to figure out how to grow enough food in order to feed everybody, and we have to do it in a responsible way. 100 10 Population increase 80 8 60 6 Annual increase (in millions) Total population (in billions) Figure 36.9A Five centuries of human population growth, projected to 2050 40 4 Total population size 20 2 1500 1550 1600 1650 1700 1750 1800 1850 1900 1950 2000 2050 Year 2

Plant Characteristics Eukaryotic Multicellular True tissues Cell walls with cellulose Mostly autotrophic, many chloroplasts in cells All reproduce sexually, but many can also reproduce asexually

Plant Classifications Presence or absence of vascular tissues and seeds distinguishes the different groups of plants. Vascular tissue- specialized structures that conduct water and dissolved materials in a plant. Similar to the blood vessels in animals, used for transporting materials throughout the plant. Seeds- structures that contain a young embryonic plant and stored food in a protective seed coat.

Plant Classifications Nonvascular Plants Vascular Plants Without Seeds Vascular Plants with Seeds

Nonvascular Plants True mosses, liverworts, hornworts These plants stay small (usually less than 2.5cm tall) due to the fact that materials must be passed from one cell to another & have no woody tissue for support. Typically found in moist shady spots Made of leafy shoots and rhizoids Rhizoids are sort of like roots but they don’t actually absorb water in mosses. Their primary purpose is anchoring the moss in place.

Moss Life Cycle Leafy shoots produce haploid gametes (sperm and egg), so the stage in the mosses lifecycle when the leafy shoots are present is called the gametophyte stage. Sperm are released and fertilize an egg which causes a sporophyte to grow (diploid) When the sporophyte capsule is mature it releases spores that are dispersed by the wind and that grow into new gametophytes when conditions are right Gametophyte is the dominant generation

Vascular Plants Without Seeds Ferns, horsetails, club mosses, whisk ferns Some are epiphytes meaning they grow on other plants but are not parasitic Most grow in cool, shaded areas. Fronds (fern leaves) grow from an underground stem called a rhizome that produces roots and can reproduce asexually.

Fern Life Cycle Spores are produced on the underside of the frond (sporophyte, diploid) Spores are released and are dispersed by the wind Spores germinate and form a tiny heart-shaped prothallus (gametophyte, haploid) The underside of the prothallus produces rhizoids (they do absorb water and minerals in ferns) which produce gametes Fertilization occurs and new fronds grow Sporophyte is the dominant generation

Vascular Plants with Seeds Angiosperm- “seed with a container (fruit)”, flowering plants Gymnosperm- “naked seed”, mostly cone-bearing plants

Pine Tree We will look at the pine tree as a representative genus for gymnosperms

Pine Tree Life Cycle Sporophyte is the dominant generation Pine trees produce pollen cones and seed cones in the spring Small pollen cones usually found toward the tips of branches produce pollen which contains the male gametes. Released pollen is carried by the wind and lands on the open scales of small green seed cones either on the same tree or another tree Seed cones close tightly once pollen is transferred. Then fertilization occurs and the seed develops Later the seed cone opens and releases the seeds when the environmental conditions are right Sporophyte is the dominant generation

Angiosperms “seed with a container (fruit)”, flowering plants An ovary of a plant is the structure that encloses the seeds, and a mature ovary is called a fruit (apple, cherry, tomato, pea pod, corn kernel… see p.338) A banana is technically a berry A strawberry technically is not a berry

Seed Dispersal Seed dispersal is important otherwise the new plants would all compete against each other and the parent plant Humans and some animals carry fruits to other areas where they eat the fruit and discard the seeds Some seeds have heavy protective coats and are able to pass through animals digestive tracts undamaged Some fruits have sticky coatings or hooks and hitch a ride on passing animals Some fruits are designed to be dispersed by the wind

The Flower Pedicel- the stalk that supports the flower Receptacle- enlarged end of the pedicel that bears the remainder of the flower parts Sepals- often green, “small petals” Petals- large and brightly colored, located just inside the sepals

The Flower Stamen consists of a stalk (filament) tipped by an anther Anther is where pollen is produced via meiosis Pollen grains house cells that develop into sperm Carpel or pistil consists of a long slender neck (style) with a sticky stigma at its tip Stigma catches the pollen At the base of the carpel is the ovary which contains one or more ovules. Each ovule contains a developing egg

Pollination Pollination- process where pollen is transferred from the anther to the stigma Vibrantly colored flowers and nectar attract pollinators Some plants’ pollen is transferred by the wind so they lack showy petals and nectar

Fertilization When pollen lands on the stigma of the right species it stimulates the formation of the pollen tube Pollen has 3 nuclei. One of those nuclei contains the information for the pollen tube. The other two nuclei are sperm nuclei. Pollen tube grows down the style, enters the ovary, and then the ovule One sperm nucleus fuses with the egg cell to form a diploid zygote The other sperm nucleus fuses with two nuclei from the ovule forming the endosperm which will provide food for the embryonic plant. Because seed formation requires the fertilization of two nuclei in the ovary by two sperm nuclei, it is termed double fertilization, and it occurs only in angiosperms.

Germination The beginning of the growth of an embryonic plant within a seed. Occurs when environmental conditions are right: proper moisture, temperature, and oxygen

Monocots and Dicots Cotyledon- contains stored food to nourish the embryonic plant while it is in the seed and to supply the young sprout with energy until it can carry on photosynthesis Monocots have one and dicots have two There are other common characteristics found among monocots and dicots

Leaf Anatomy Stomata Lab http://www.sciencedaily.com/terms/vegetable.htm https://www.youtube.com/watch?v=ExaQ8shhkw8