gymnosperms. gymnosperm facts - the late tracheophytes are the gymnosperms and angiosperms....

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Page 1: Gymnosperms. Gymnosperm Facts - The late tracheophytes are the Gymnosperms and Angiosperms. Gymnosperms and Angiosperms are the Seed Plants. - Gymnosperms

Gymnosperms

Page 2: Gymnosperms. Gymnosperm Facts - The late tracheophytes are the Gymnosperms and Angiosperms. Gymnosperms and Angiosperms are the Seed Plants. - Gymnosperms

GymnospermFacts

- The late tracheophytes are the Gymnosperms and Angiosperms. Gymnosperms and Angiosperms are the Seed Plants.

- Gymnosperms bear cones and have naked seeds. The seeds are termed “naked” because they are not enclosed by fruit as in the angiosperms.

Giant Sequoias

- Seeds are exposed on modified leaves that form cones.

- Gymnosperms are heterosporous. They have pollen and seeds and almost all gymnosperms are woody.

- Gymnosperms depend on wind for pollination.

- Gymnosperm Examples: pines, firs, redwoods, junipers and sequoia.

Page 3: Gymnosperms. Gymnosperm Facts - The late tracheophytes are the Gymnosperms and Angiosperms. Gymnosperms and Angiosperms are the Seed Plants. - Gymnosperms

Division Coniferophyta

Division Gnetophyta

Division Ginkgophyta

Division Cycadophyta

A Cladogram of the Gymnosperms.

Page 4: Gymnosperms. Gymnosperm Facts - The late tracheophytes are the Gymnosperms and Angiosperms. Gymnosperms and Angiosperms are the Seed Plants. - Gymnosperms

Gymnosperm EvolutionGymnosperms were the first seed plants to

appear-millions of years before the first angiosperms. The conifers replaced many ferns as Earth's climate became more arid because conifers are better adapted for a dry environment. These modifications for a dry environment include needle-shaped leaves, which have a thick, protective cuticle and a relatively small surface area. Seed and pollen found in gymnosperms are key reproductive innovations for life on land (water is not necessary for sperm to reach egg like in the early tracheophytes).

Page 5: Gymnosperms. Gymnosperm Facts - The late tracheophytes are the Gymnosperms and Angiosperms. Gymnosperms and Angiosperms are the Seed Plants. - Gymnosperms

Division Cycadophyta – The Cycads

Sago Palm (Cycas revoluta)

Cycads were very important in the Mesozoic Era. The were important for herbivorous dinosaurs. Today, they are not so diverse. They are palm-like.

Zamia sp. with ovulate (seed) cones.

Page 6: Gymnosperms. Gymnosperm Facts - The late tracheophytes are the Gymnosperms and Angiosperms. Gymnosperms and Angiosperms are the Seed Plants. - Gymnosperms

Division Ginkophyta – The GinkgoOnly 1 living species, the ginkgo tree. It tolerates pollution and is an urban street tree. Ginkgo is dioecious. Pollen trees are preferred. The fruit of seed trees smell really bad. So what would plant in your yard, a male or female tree?

Ginkgo Tree (Ginkgo biloba)

Also known as the madenhair tree.

Page 7: Gymnosperms. Gymnosperm Facts - The late tracheophytes are the Gymnosperms and Angiosperms. Gymnosperms and Angiosperms are the Seed Plants. - Gymnosperms

Division Gnetophyta – Gnetum, Welwitchsia, Ephedra

These gymnosperms have vessel elements like the flowering plants.

Welwitschia mirabilis

Page 8: Gymnosperms. Gymnosperm Facts - The late tracheophytes are the Gymnosperms and Angiosperms. Gymnosperms and Angiosperms are the Seed Plants. - Gymnosperms

Division Coniferophyta (Pinophyta) – The Conifers “Cone-bearers”

- Many conifers have woody cones. Pine is an example of this.

- Some lack woody cones and have a berry-like tissue around seeds.

Fascicles of needles born or short shoots from a pine (Pinus sp.).

Eight families are found in this division.

The pine family (Pinaceae) includes the pines, fir and spruce.

Page 9: Gymnosperms. Gymnosperm Facts - The late tracheophytes are the Gymnosperms and Angiosperms. Gymnosperms and Angiosperms are the Seed Plants. - Gymnosperms

Gymnosperm ReproductionEach individual tree generally has both cone types

(male and female). Therefore these trees are monoecious.

Small pollen cones produce microspores that develop into male gametophytes or pollen grains. Larger ovulate cones usually develop on separate branches of the tree and produce megaspores that develop into female gametophytes.

Strobilus (plural, strobili) – a number of modified leaves (sporophylls) or ovule bearing or pollen bearing scales grouped together on an axis; papery; pollen is produced here; part of pollen cone.

Pollen grain is the immature male gametophyte.Ovulate cone (female) – when young it is softer and

smaller than the male strobilus.Pollination replaces the need for free water, which is

necessary in early tracheophyte reproduction.

Page 10: Gymnosperms. Gymnosperm Facts - The late tracheophytes are the Gymnosperms and Angiosperms. Gymnosperms and Angiosperms are the Seed Plants. - Gymnosperms

Mature Ovulate (female) cones of Shasta red fir. Cones in this genus are borne upright. Note the long bracts projecting beyond the cone scales.

Page 11: Gymnosperms. Gymnosperm Facts - The late tracheophytes are the Gymnosperms and Angiosperms. Gymnosperms and Angiosperms are the Seed Plants. - Gymnosperms

Douglas Fir (Pseudostuga menziesii) with soft needles and cone.

Page 12: Gymnosperms. Gymnosperm Facts - The late tracheophytes are the Gymnosperms and Angiosperms. Gymnosperms and Angiosperms are the Seed Plants. - Gymnosperms

Pollen (Male) StrobiliA cluster of strobili near the end of a branch at the time of pollen release.

A longitudinal section of one strobilus, showing microsporangia attached to the underside of each scale.

Each microsporangium is filled with pollen grains; the pollen grains consist of only 2 cells; each with its own nucleus.

Page 13: Gymnosperms. Gymnosperm Facts - The late tracheophytes are the Gymnosperms and Angiosperms. Gymnosperms and Angiosperms are the Seed Plants. - Gymnosperms

Ovulate (Female) Cones at Time of Pollination

2- Month-Old cones at the tip of a young branch. Below are large cones just older than 1 year.

Longitudinal section through a 2-month-old cone, showing ovules on top of each scale.

A closer view of one ovule (dashed area). Note the large megasporocyte inside the nucellus and the micropyle and micropylar chamber. Meiosis has not yet occurred.

The mature open cone is 2 years old when seeds are mature.

Page 14: Gymnosperms. Gymnosperm Facts - The late tracheophytes are the Gymnosperms and Angiosperms. Gymnosperms and Angiosperms are the Seed Plants. - Gymnosperms

Life Cycle of Pine A Representative Gymnosperm.

(a) A young ovulate (seed) cone.

(b) A scale from an ovulate cone with 2 ovules on its upper surface.

(c) Longitudinal section of an ovulate cone at the time of pollination.

(d) A pollen strobilus

(e) One scale from a pollen strobilus

(f) A section of a microsporangium with mature pollen grains inside.

(g-i) A developing male gametophyte.

(c,j,k) A developing female gametophyte.

(l-n) A developing seed.

(o) Germination of the seed.

Page 15: Gymnosperms. Gymnosperm Facts - The late tracheophytes are the Gymnosperms and Angiosperms. Gymnosperms and Angiosperms are the Seed Plants. - Gymnosperms

Ecological and Economic Importance of Gymnosperms

The gymnosperm landscape covers the 1/3 of the landmass of North America.

The presence of gymnosperms can cause acidic or nutrient poor soil by presence of decaying pine needles.

The harvesting of ponderosa pine, eastern white pine and Douglas fir is important to the forestry economy.

Page 16: Gymnosperms. Gymnosperm Facts - The late tracheophytes are the Gymnosperms and Angiosperms. Gymnosperms and Angiosperms are the Seed Plants. - Gymnosperms

BIO 141 Botany with Laboratory

• This product is sponsored by a grant awarded under the President’s Community-Based Job Training Grants as implemented by the U.S. Department of Labor’s Employment and Training Administration. The information contained in this product was created by a grantee organization and does not necessarily reflect the official position of the U.S. Department of Labor. All references to non-governmental companies or organizations, their services, products, or resources are offered for informational purposes and should not be construed as an endorsement by the Department of Labor. This product is copyrighted by the institution that created it and is intended for individual organizational, non-commercial use only.