Gymnosperms

seed-scale complex

found in conifer ovulate cones; each contains sterile bract and ovulate scales that produce 2 ovules on the upper surface

integument

outer layers of tissue that surround the nucellus; the outmost layers; becomes a seed coat after fertilization and development of an embryo takes place

Cycadophyta

palmlike gymnosperms: central pith, leaves clustered at top of wood trunk; separate male and female plants; one of the few surviving gymnosperms; found in tropics and subtropics

microsporangiate cone

pollen cones, the structure in gymnosperms in which the microspores are formed: corresponds to the pollen sac in seed plants; papery or membranous scales arranged in a spiral or in whorls around an axis; develop towards tips of lower branches in clusters

ovuliferous scale

A spiral series of overlapping scales making up the female or ovulate cone with each scale producing two ovules on the upper surface, which develop into seeds

c. Pinaceae • Pine trees • Cone location design so as to not self-fertilize • Male and female sporangium cones on the same tree • Water not needed for reproduction • Fascicles of leaves • Xylem and phloem • Pollen Leptosporangiate ferns • Ferns • Sporus (clusters for sporangia) • Megaphylls (true leaves) • Water required for reproduction • Do not self fertilize • No pollen • No seeds Both: • Hetersporous • Do not self fertilize • Stems and true leaves • Supporting tissues

Compare and contrast Pinaceae and Leptosporangiate ferns

more or less the same as 34

Compare and contrast Pinaceae and Lycopodium

b. Pinaceae • Pine trees • Heterosporous • Cone location design so as to not self-fertilize • Male and female sporangium cones on the same tree • Water not needed for reproduction • Fascicles of leaves • Xylem and phloem • pollen Lycophytes: • Club mosses • Homosporous • Water needed for reproduction • Kidney-shaped sporangia • No supporting tissues • No pollen Both: • No fruits or flowers • Do not self fertilize have megaspores and microspores

Compare and contrast Pinaceae and Selaginella (Lycophytes)

Pinaceae: • Pine trees • Heterosporous • Cone location design so as to not self-fertilize • Male and female sporangium cones on the same tree • Water not needed for reproduction • Fascicles of leaves • Xylem and phloem • pollen megaspores and microspores Mosses: no xylem and phloem no leaves archegonium and antheridium water required for fertilization Both: chlorophyll a & b male and female gametophytes

Compare and contrast Pinaceae and moss

The female megaspore mother cell divides by meiosis to produce 4 haploid spores. 3 of these will die off and leave a female gametophyte that is retained on parent plant. the female gametophyte of gymnosperms is a large and multicellular structure and serves as the double function of bearing the gametes and providing nourishment of the developing embryo. The female gametophyte contains two or three groups of cells called archegonia, each of which contains a large egg nucleus.

Describe the structure of a female gametophyte in a pine.

A male cone contains microsporophylls where male gametophytes (pollen) are produced and are later carried by wind to female gametophytes Pollen develops from the microspore mother cells. The mature pollen grain is composed of two cells: the pollen tube cell and the generative cell, which is inside the tube cell. The mature pollen grain (1n) is winged in many gymnosperms, a feature that facilitates air transport

Describe the structure of a male gametophyte in a pine.

An ovule is composed of megasporangium with functional megaspore and integuments. It consists of three layers: 1. integument (outer layers) - diploid 2. nucellus (remnant of megapsorangium) - diploid 3. gametophyte (megaspore) - haploid It has a small opening called the micropyle

Describe the structure of an ovule.

The pine cones typically thought of as pine cones are actually the bigger female pine cones; male pine cones are not as woody and are much smaller in size. Female pine cones hold the seeds whereas male pine cones contain the pollen. Most conifers, or cone-bearing trees, have female and male pine cones on the same tree. A female pine cone, also called a megasporangiate strobilus, consists of cone or seed scales that hold two ovules; it has spirally arranged modified branches known as the seed-scale complex. Male pine cones are usually yellowish because of the pollen dust. Male cones exist in clusters on the tips of the branches of pine trees. Has spirally arranged microsporophylls.

Describe the structure of male and female cones. List the ways male and female pine cones are different.

A seed is made up of a diploid seed coat, a female gametophyte (haploid), nucellus (2n), and a diploid embryo. The two diploid tissues result from two integuments that develop into the seed coat after fertilization. The embryo then forms from the female gametophyte to be the young sporophyte and a new diploid generation.

Describe the structure of seed. There is tissue from two diploid generations in a seed. Explain.

Liverworts, mosses, hornworts independent sporophyte and true xylem and phloem Lycophytes true leaves (megaphylls) Ferns ovules and seeds, heterosporous Gymnosperms Angiosperms Required Water: mosses, liverworts, hornworts, ferns, lycophytes Sporophyte dominant: ferns, lycophytes, gymnosperms, angiosperms

Draw a tree that shows how the following groups of organisms are related to each other: mosses, liverworts, hornworts, ferns, lycophytes, gymnosperms, angiosperms. Place the synapomorphies that define each group on the tree. In which groups is the sporophyte dominant? In which groups is water required for fertilization.

Ginkgophyta

Fan-shaped leaves, dichotomous venation, long and short shoots, deciduous (loses leaves for part of year), separate male and female plants

Seed plants have secondary xylem and phloem. They are heterosporous, which means they produce two types of independent spores. Lastly, they have ovules and seeds

List and briefly describe the synapomorphies that define the Gymnosperms and Angiosperms.

Adaptations for terrestrial life include xylem and phloem, seeds, and no water is required for fertilization. True xylem and phloem allow nutrients to be carried throughout the plant and allows the cell to acquire nutrients much more easily. Seeds increase offspring survival. It protects an enclosed embryo, provides nourishment for embryo, prevents embryo from drying out, and allows higher germination rates. No water required for fertilization allows plants to grow in arid and diverse environments.

List the adaptations to life in a terrestrial environment that are found in seed plants. Explain survival advantage of each trait.

Gnetophyta

Sister group to pine family. division of plants, within the gymnosperms with 70 species across the three relict genera: Gnetum, Welwitschia, and Ephedra; have angiosperm-like features; similar vessels in xylem, strobili similar to flower clusters; double fertilization; no archegonia in first 2 types

megagametophyte

The female gametophyte that arises from a megaspore of a heterosporous plant. produces more than one archegonium

ovule

The female reproductive structure that develops into a seed in a seed-bearing plant; consists of a megasporangium surrounded by one or two layers of tissue called integuments. (seed coat, embryo, stored food) a small egg in seed plants that has three parts: integument, nucellus, and female gametophyte; contains the female reproductive cells

Sporic life cycle because they have an alternation of generations between haploid gametophyte and diploid sporophyte. Gymnosperms have a sporophyte dominant life cycle. This means the gametophyte is short lived. Two spore types, microspores and megaspores, are produced in pollen cones and ovulate cones, respectively. The main body of a gymnosperm is a sporophyte and is diploid. This means that because the majority of its life is spent as a diploid sporophyte it has a sporophyte dominant life cycle.

What type of life cycle do gymnosperms have? Explain.

secondary xylem

Woody tissue is made of secondary xylem produced by the vascular cambium

Gymnosperms

a group of seed-producing plants that includes conifers, cycads, Ginkgo, and gnetophytes. ovules and seeds exposed on sporophylls or analogous structures (not enclosed in an ovary)

seed

a mature ovule with a sporophyte (2n) embryo. composed of outer, diploid seed coat, diploid nucellus, haploid megagametophyte, and developing diploid embryo. Increases offspring survival Protects enclosed embryo Source of nourishment for embryo Prevents embryo from drying out

pollen grain

a microscopic body that contains the male reproductive cell of a plant; produces two sperm. microgametophyte

bract

a specialized leaf or leaflike part just below an inflorescence, flower stalk, or flower

megasporangium

produces spores that develop into megaspores and then megagametophytes. diploid; nucellus; fleshy tissue surrounding the ovule

megasporangiate cone

seed cones, the structure in gymnosperms in which the megaspores are formed: corresponds to the ovule in seed plants; much larger than pollen cones; woody scales with inconspicuous bracts between them arranged in a spiral around the axis; produced on upper branches of the same trees as pollen cones

short shoot

sometimes called "spurs," slowly growing reproductive shoots

long shoot

sometimes called "watersprouts," rapidly growing vegetative shoots

secondary phloem

the inner bark; produced by the vascular cambium; sieve cells

megaspore

the larger of the two kinds of spores. the female spore of Gymnosperms

heterospory

the production of spores of two different sizes and sexes by the sporophytes of land plants. The smaller of these, the microspore, is male and the larger megaspore is female

seed coat

the protective outer coat of a seed; diploid; develops from the integument after development of an embryo through fertilization;

Coniferophyta

woody plants commonly known as the "conifers;" found in temperate and mountain forests; have eustele in stem; heterosporous; produce ovules that mature into seeds. These ovules and seeds are found on the upper surfaces of scale structures which often are clustered into "cones"

embryo

young sporophyte of Gymnosperms (2n)