Bot-Lab (Sem-1) - Chapter 6: Gymnosperms

seed

provide a much better protection to the plant embryo; produced by gymnosperms and angiosperms

spermatophytes

gymnosperms and angiosperms; produces seeds

seed production; wood production

two major improvements of previous plant lineages that are found in gymnosperms

wood production

allow gymnosperms and angiosperms to grow taller and become better competitors in their habitats

gymnosperm

literally means “naked seed” in reference to their seeds being borne out in the open on cone scales of a sporophyte plant

excurrent branching pattern

trunk only divides when the terminal bud is removed

terminal bud

a bud located at the apex of the stem where most of the plant growth occurs

evergreen leaves

most gymnosperms have _________ ______, in which foliage remains green and functional all throughout the year

2; 5

conifers may have a total change of leaves every - years

Cycadophyta (cycads); Ginkgophyta (maidenhair tree); Pinophyta (conifers); Gnetophyta (gnetophytes)

four major phyla of gymnosperms; follow this format: Phylum (subset/group)

Late Devonian period (375-400 MYA)

when gymnosperms arose

Mesozoic Era - late Cretaceous Period (70 MYA)

when gymnosperms dominated land vegetation

65; 720

known number of genera and species to exist at present

Phylum Cycadophyta

a relatively ancient group of plants that were once much more common than today and served as fodder for plant-eating non-avian dinosaurs

cycads

seed plants that typically have a stout and woody trunk with a crown of large, hard, stiff, evergreen and pinnate leaves

cycad (male cone)

a microsporophyll; produce pollen, which is carried by wind to female cones (borne on separate plants), where fertilization occurs

cycad (seed)

produced by female cycads; edible

Cycas revoluta (sago palm)

under Cycadophyta

x-s midrib Cycas revoluta

identify the prepared slide

vascular tissues

what is the encircled part of the x-s midrib Cycas revoluta called?

mature ovule

a small structure present in the ovary of Cycas; forms the seed; consists of a food tissue covered by one or two future seed coats, known as integuments

micropyle

identify the part labeled with a question mark; a small opening in the surface of an ovule, through which the pollen tube penetrates, often visible as a small pore in the ripe seed

pollen chamber

identify the part labeled with a question mark; a small chamber at the apex of the nucellus in some plants (as most gymnosperms) for the reception of the pollen

nucellar beak

identify the part labeled with a question mark; a proboscis-like outgrowth of the nucellus at the micropylar end, being the obligatory path for the pollen tube entering the ovule

nucellus

identify the part labeled with a question mark; the central part of an ovule, containing the embryo sac

integument

identify the part labeled with a question mark; a tough outer protective layer, especially that of an animal or plant

10

number of extant genera of cycads

extant

opposite of extinct; still in existence; surviving

100

number of species of cycads

palm trees

what cycads resemble superficially; belonging to the family Arecaceae

pinnate leaves

attached to short stems; a type of compound leaf that has a central stem with small leaves arranged on either side of it

dioecious

having the male and female reproductive organs in separate individuals

microsporophyll

part of the male cycad cone that bear pollens containing motile sperms

motile sperm

sperm that have the ability to move or swim efficiently through the female partner’s reproductive system in order to fertilize an egg

megasporophyll

part of the female cycad cone that is modified to bear the ovules which eventually become seeds

integument

a tough outer protective layer, especially that of an animal or plant

archegonium

where the egg is borne inside in

megasporangium

where the archegonium is found

Phylum Ginkgophyta

a phylum consisting of only one living species (Ginkgo biloba)

Ginkgo biloba

an ancient plant dating back to the Carboniferous times (290 MYA) with very little change; this species is a temperate species originating from China; fan-shaped leaves with dichotomous venation; dioecious

x-s leaf Ginkgo

identify the prepared slide

a.) cuticle; b.) upper epidermis; c.) vascular tissues; d.) lower epidermis; e.) guard cells; f.) spongy parenchyma cells; g.) xylem; h.) phloem

label the parts of the Ginkgo leaf; use this format: a.) answer; b.) answer; etc etc

x-s leaf (stalk) Ginkgo

identify the prepared slide

a.) epidermis; b.) stomata; c.) resin ducts/canals; d.) mesophyll; e.) xylem; f.) phloem; g.) endodermis

label the parts of the Ginkgo leaf stalk; use this format: a.) answer; b.) answer; etc etc

deciduous

shreds leaves annually

Carboniferous times (290 MYA)

from when the ancient ginkgo plant dates back to with very little change

China

country of origin of ginkgo

dichotomous venation

of ginkgo; veins fork by twos extending from a common point forming a “y” pattern fanning out

hypodermal sclerenchyma

tissue that makes the plant hard and stiff

hypodermis

lies beneath the epidermis

ginkgo leaf

contains a thin-walled epidermis and lacking a hypodermal sclerenchyma

guard cells

of ginkgo; slightly depressed and occur only on the abaxial side; pairs of epidermal cells that control gas diffusion by regulating the opening and closure of stomatal pores

abaxial side

the underside or side facing away from the stem

stomata

a pore found in the epidermis of leaves, stems, and other organs, that controls the rate of gas exchange between the internal air spaces of the leaf and the atmosphere

mesophyll

consists of one-cell layer palisade of short lobed cells and a spongy parenchyma

parenchyma

tissue typically composed of living cells that are thin-walled, unspecialized in structure, and therefore adaptable, with differentiation, to various functions

lumen

the compartment where molecular oxygen is produced from water during photosynthetic light-dependent reactions

palisade

a layer of plant cells containing chloroplasts right below the epidermis in plants

lignified endodermis

plant tissue in the roots of vascular plants between the periderm and the cortex

tannins

of ginkgo; abundant in the endodermal sheath; complex chemical substances derived from phenolic acids

transfusion tracheids

of ginkgo; to transport water and inorganic salts, and to provide structural support for trees

mucilage ducts

of ginkgo; found alternating with the vascular bundles; distributed in a ring within the cortex and may also be found in the pith region

mucilage

plays a role in the storage of water and food, seed germination, and thickening membranes

resin ducts/canals

of ginkgo and conifers; elongated, tube-shaped intercellular spaces surrounded by epithelial cells which secrete resin into the canal; occur in the mesophyll and its number varies with the species

resin

of ginkgo and conifers; a mixture of organic compounds that protect tissues from microbial disease

Phylum Coniferophyta/Pinophyta

conifers; mostly woody, evergreen shrubs and trees; group of cone-bearing seed plants, a subset of gymnosperms; an important source of lumber and wood for fuel

Thuja orientalis (oriental arborvitae)

Platycladus; a monotypic genus of evergreen coniferous trees in the cypress family Cupressaceae

Araucaria heterophylla (Norfolk pine)

Pinophyta; used for Christmas trees

Pinus kesiya (Benguet pine tree)

Pinophyta; one of the most widely distributed pines in Asia

Pinus sp. conifer cone

a seed-bearing organ on gymnosperm plants; usually woody, ovoid to globular, including scales and bracts arranged around a central axis, especially in conifers and cycads

Pinus resinosa (red pine)

Pinophyta; native to Eastern North America

Pinus stem (older)

identify the prepared slide

Pinus stem (younger)

identify the prepared slide

50; 550

amount of genera and living species under Coniferophyta; most thriving in colder regions of the world

needle-shaped

shape of conifer leaves

sunken stomata

of conifers; stomata that are buried or not directly visible to the surface

sclerified fibrous hypodermis

of conifers; occurs beneath the epidermis; except under the rows of stomata

sclerification

thickening of the cell wall, increasing rigidity

transfusion tissue

of conifers; composed of tracheids and parenchyma cells; bordered by a thick-walled endodermis

ring/circle

conifer stems behave similarly to woody dicots in the sense that their vascular tissues are arranged in a ____/______ around the pith

apical meristem

give rise to the primary plant body and are responsible for the extension of the roots and shoots

vascular cambium

the main meristem in the stem, producing undifferentiated wood cells inwards and bark cells outwards

growth rings

in a cross section of the stem of a woody plant, the increment of wood added during a single growth period; tell us how old the tree is

annual rings

the layer of wood that is formed during a single growing season

softwood

lacking fibers, giving the wood a smooth, light texture

hardwood

numerous resin ducts are distributed not only in the cortex but also in the wood region

wings/air bladders

of conifers; found in Pinus pollen grain; help with the dispersal of the pollen; allow the pollen to travel farther on the wind and reach new areas and other plants

Phylum Gnetophyta

a small group of gymnospermous vascular plants that are represented by three living genera: Ephedra, Gnetum, and Welwitschia

Gnetum latifolium

an evergreen plant in the family Gnetaceae with a broad distribution across South East Asia

Ephedra foliata (shrubby horsetail)

Gnetophyta; a species of gymnosperm in the Ephedraceae family

Ephedra foliata (transverse section)

identify the prepared slide

Ephedra foliata (tangential section)

identify the prepared slide

Ephedra foliata (radial section)

identify the prepared slide

3; 70

number of genera and species in Phylum Gnetophyta

Gnetum

have broad leaves and live mostly in the tropics as vines or trees