Lab Pine Lifecycle Lilly Lifecycle

Dates for plant group origins: Mosses 475 Ferns 420 Gymnosperms 360 Angiosperms 160

The Pine Life cycle Fig. 30.9

Gnetum Ephedra Ovulate cones Welwitschia PHYLUM GNETOPHYTA PHYLUM CYCADOPHYTA PHYLUM GINKGOPHYTA Cycas revoluta

Douglas fir Pacific yew Common juniper Wollemia pine Bristlecone pine Sequoia PHYLUM CONIFEROPHYTA

Gnetophytes 3 genera: Welwitschia, Ephedra, Gnetum Mostly dioecious Have more Similarities to angiosperms: –Have vessel elements, –Lack archegonia (except Ephedra) –Two sperm nuclei in pollen. Fertilizes two eggs in some groups. Analogous to double fertilization n angiosperms Morphologically diverse group, grouped by genetic comparisons Common ancestral pool long gone, a few remote descendents remaining.

Gingko biloba Dioecious, heterosporous Dichotomous venation Deciduous

Cycads Leaves look like palms, ferns Makes cones Dioecious, herterosporous Pollen tube produces sperm inside !!

Pollen (Staminate) Cone: Produced yearly Short lived- die after releasing pollen Different species release pollen at different times to avoid hybridization The male cone has the microsporangia on scale-like sporophylls. –(n) microspores from by meiosis –They develop into pollen grains –Produces millions of pollen grains per branch Carried by wind- random mating

Pollen are the male gametophytes –just 4 cells ! –generative cell forms the pollen tube –Pine pollen have wing cells to keep them afloat in air are covered with a tough sporopollenin. are carried away by wind or animals until pollination occurs. pollen grain will elongate a tube into the ovule and deliver sperm (nuclei) into the female gametophyte via pollen tube No longer need film of water to fertilize

Ovulate cone very small and fleshy when young Forms the “Pine Cone” with seeds –often matures over 2-3 years form on branch tips to catch pollen 2 megasporangia form on each scale or sporophyll –Megasporangia form 2 ovules –They become the 2 mature seeds per scale in the pine cone

Ovule Forms inside female (ovulate) cone Megasporangia on sporophylls under go meiosis – one surviving (n) megaspore. Megaspore grows inside by mitosis integuments (2n) to become female gametophyte –With 3 archegonia and eggs (pine). Zygote develops into embryo, inside nutritive female gametophyte tissue. Embryo goes dormant, integuments harden and ovule now becomes a seed

Pine ovule

Pine Megasporangia : ovulate cone

Pine Ovule; female gametophyte & Archegonia

Pine Microsporangia & pollen

Staminate Ovulate

Pine pollen & pollen tube

Angiosperms Flowers – attract pollinators Ovary = Fruit Ovules ( inside)=seeds

The flower Sepals Petals Stamens (male) –Anther - pollen –Filament Carpel (female) –Stigma –Style –Ovary –Ovule-eggs

Figure Flower-pollinator relationships A flower pollinated by honeybees. This honeybee is harvesting pollen and Nectar (a sugary solution secreted by flower glands) from a Scottish broom flower. The flower has a tripping Mechanism that arches the stamens over the bee and dusts it with pollen, some of which will rub off onto the stigma of the next flower the bee visits. (a) A flower pollinated by nocturnal animals. Some angiosperms, such as this cactus, depend mainly on nocturnal pollinators, including bats. Common adaptations of such plants include large, light-colored, highly fragrant flowers that nighttime pollinators can locate. (c) A flower pollinated by hummingbirds. The long, thin beak and tongue of this rufous hummingbird enable the animal to probe flowers that secrete nectar deep within floral tubes. Before the hummer leaves, anthers will dust its beak and head feathers with pollen. Many flowers that are pollinated by birds are red or pink, colors to which bird eyes are especially sensitive. (b)

The life cycle of an angiosperm Nucleus of developing endosperm (3n) Zygote (2n) FERTILIZATION Embryo (2n) Endosperm (food supply) (3n) Seed coat (2n) Seed Germinating seed Pollen tube Sperm Stigma Pollen grains Pollen tube Style Discharged sperm nuclei (n) Egg nucleus (n) Mature flower on sporophyte plant (2n) Key Haploid (n) Diploid (2n) Anther Ovule with megasporangium (2n) Male gametophyte (in pollen grain) Microspore (n) MEIOSIS Microsporangium Microsporocytes (2n) MEIOSIS Generative cell Tube cell Surviving megaspore (n) Ovary Megasporangium (n) Female gametophyte (embryo sac) Antipodal cells Polar nuclei Synergids Egg (n) Pollen tube Sperm (n)

Gametophyte growth

Angiosperm seed formation

Flower cross section # 52 Ovules Pistil Anthers Petals Sepals

Germinating pollen

Lilly Anther