1.0 Introduc Introduction tion
"Gymnosperms" include all seed plants other than the angiosperms, or flowering plants. The absence of an enclosing structure is believed to be primitive, thus the first seed plants were "gymnosperms." The seeds of "gymnosperms" are borne exposed in open structures, such as cones or leaves. The derivation of the word "gymnosperm" means naked seeds and is from the Greek words gymno meaning naked or bare and spermmeaning seed. Fossil records indicate "gymnosperms" originated in the Paleooic !ra, during the middle evonian Period about #$% million years ago, and reached their greatest diversity during the &esooic !ra, between '% to (() million years ago. *lthough the "gymnosperms" were at one time treated as one closely allied group, many modern workers recognie several ma+or groups, which include the commonly known conifers, cycads, and ginkgos, and the lesser known gnetopsids group, extinct progymnosperms, and extinct seed ferns. -ilton, et.al., (%%/.
The angiosperms, or flowering plants, are one of the ma+or groups of extant seed plants and arguably the most diverse ma+or extant plant group on the planet, with at least ('%,%%% living species classified in 0)# families 1udd et al., (%%(2 *PG 33, (%%#2 4oltis et al., (%%)/. They occupy every habitat on !arth except extreme environments such as the highest mountaintops, the regions immediately surrounding the poles, and the deepest oceans. They live as epiphytes i.e., living on other plants/, as floating and rooted a5uatics
in both freshwater and marine habitats, and as terrestrial plants that vary tremendously in sie, longevity, and overall form. They can be small herbs, parasitic plants, shrubs, vines, lianas, or giant trees. There is a huge amount of diversity in chemistry often as a defense against herbivores/, reproductive morphology, and genome sie and organiation that is unparalleled in other members of the Plant 6ingdom. Furthermore, angiosperms are crucial for human existence2 the vast ma+ority of the world7s crops are angiosperms, as are most natural clothing fibers. *ngiosperms are also sources for other important resources such as medicine and timber. 8ole, et.al., (%%$/.
9b+ectives of this experiment are to describe the features of seed plant life cycle and the concept of the dominant generation, to describe the life histories and related reproductive structures of gymnosperms and angiosperms, to summarie the features that distinguish gymnosperm and angiosperm, and to discuss the advantages of seed plants to dominate land and their evolutionary adaptations of land.
2.0 Materials (.: Gymnosperm (.:.: ;iving specimens of gymnosperm (.:.( 8ompound microscope (.:.# issecting microscope (.:.0 4lide and coverslip (.:.) Forceps (.:.' istilled water
(.( *ngiosperm (.(.: ;iving specimens of angiosperm < (.(.:.: icots and monocots with rots, stems, leaves,
(.(.( (.(.# (.(.0 (.(.) (.(.'
flowers, fruits and seeds 8ompound microscope issecting microscope 4lide and coverslip Forceps istilled water
3.0 Procedure #.: Gymnosperm #.:.: Pine #.:.:.: ifferentiate between male and female cone of Pinus sp. #.:.:.( ;ongitudinal section of female and male cone
examined. &egasporopyll, microsporophyll, megasporangia, microsporangia, ovule and pollen grains. #.:.:.# !xamined the fertiliation occurred. #.:.:.0 &ature seed cone obtained. #.:.:.) *notomy of pine leaf examined. !pidermis,
stoma, photosynthetic mesophyll, endodermis, phloem, xylem, and resin duct identified.
#.( *ngiosperm #.(.: ;eaves #.(.:.: &orphology of leaf arrangements and leaf venation. #.(.:.( 4tructure of the leaves studied. 8ommon features such as cuticle, air space, lower epidermis, upper epidermis, palisade mesophyll, spongy mesophyll, and vascular bundle. #.(.(
Flowers #.(.(.: ;ongitudinal section of some flowers observed. Parts of the flower named such as stigma, pistil, style, ovary, sepal, receptacle, peduncle, petal, filament stamen, and anther.
#.(.#
Fruits and 4eeds #.(.#.: Fruit wall, cotyledon, plumule of embryo, embryo, radical, cotyledon, seed coat, pericarp, mesocarp,endocarp, locule, and placenta identified.
4.0 Results 0.: Gymnosperm
Pine
0.( *ngiosperm 0.(.: ;eaves
0.(.(
Flowers
-ibiscus
*llamanda
0.(.#
Fruits and seeds
1ackfruit
;angsat
*pple
=anana
Pineapple
9range
8orn
Guava
5.0 Post Lab Questions ).: -ow to distinguish between a male and female cone of pine> The &ale cone will form at the bottom of the tree and is much smaller
than
the
female
and
the
male
produces
the
pollen
and the female, produces the ovul and forms at the top of the tree. ).( !xplain the characteristics of gymnosperm seeds to aid in dispersal. ?nlike animals, plants are limited in their ability to seek out favorable conditions for life and growth. *s a result, plants have evolved many ways to disperse their offspring by dispersing their seeds see also vegetative reproduction/. * seed must somehow "arrive" at a location and be there at a time favorable for germination and growth. @hen the fruits open and release their seeds in a regular way, it is called dehiscent, which is often distinctive for related groups of plants2 these fruits include capsules, follicles, legumes, silicles and sili5ues. @hen fruits do not open and release their seeds in a regular fashion, they are called indehiscent, which include the fruits achenes, caryopsis, nuts, samaras, and utricles. 4eed dispersal is seen most obviously in fruits2 however, many seeds aid in their own dispersal. 4ome kinds of seeds are dispersed while still inside a fruit or cone, which later opens or disintegrates to release the seeds. 9ther seeds are expelled or released from the fruit prior to dispersal. For example, milkweeds produce a fruit type, known as a follicle, that
splits
open
along
one
side
to
release
seeds. 3ris capsules split into three "valves" to release their seeds
).# ;ist the common characteristics of seed plants.
the
*ll seed plants share two characteristics. They have vascular tissue and use seeds to reproduce. 3n addition, they all have body plans that include leaves, stems, and roots. &ost seed plants live on land. 4eed plants face many challenges, including standing upright and supplying all their cells with water and food. They meet these two challenges with vascular tissue. The thick walls of the cells in the vascular tissue help support the plants. 3n addition, water, food, and nutrients are transported throughout the plants in vascular tissue. There are two types of vascular tissue. Phloem is the vascular tissue through which food moves. @hen food is made in the plant7s leaves, it enters the phloem and travels to the plant7s stems and roots. @ater and nutrients, on the other hand, travel in the vascular tissue called xylem .The plant7s roots absorb water and nutrients from the soil. These materials enter the root7s xylem and move upward into the plant7s stems and leaves. 4eeds are structures that contain a young plant inside a protective coating. 9ne reason why seed plants are so numerous is that they produce seeds. 4eed plants do not need water in their environment to reproduce like seedless plants do. !ven though different kinds of seeds look different from each other, they all have a similar structure. * seed has three important parts< an embryo, stored food, and a seed coat.
).0 8ontrast between dicots and monocots, the two classes of flowering plant. * dicot seed will look like a bean with two parts. &onocots have parallel venation, fibrous root systems, lack true woody growth, flower parts come in multiples of threes, stems have scattered vascular bundles, pollen has
one spore. !xample < Palm trees, grasses, banana plants, orchids, bamboo, bromeliads. icots have net venation, taproot system, ma have woody growth, vascular bundels are in a ring, pollen has # spores, flowers in parts of 0 or ). !xample <9ak trees, tomato, lettuce, hibiscus, roses, apple tree. ).) iscuss the features of plant flowering fruits and seeds. 4eeds develop from ovules in the ovary, and at maturity consist of an embryo and a reserve food supply surrounded by a protective covering, the seed coat. The diversity of flowering plants assures div ersity among their seeds, but, unlike fruits, which have numerous variations, structural plans for seeds are few. The reserve food can be stored either in or out of the embryo and the cotyledons/Athe seed leavesAcan remain either below ground or be elevated above the surface when germination occurs. Fruits are ripened ovaries containing seeds with sometimes additional flower or inflorescence tissues associated with them. 9nly angiosperms produce flowers and fruits. From a botanical viewpoint, many of the foods we eat as vegetables are fruits, e.g. tomatoes, green beans, s5uash, eggplant, and peppers. Fruits apparently arose as a means not only of protecting the seeds, but as a way to ensure their dispersal.
.0 !onclusion
".0 Re#erences
