Vegetative Reproduction
Bulbs: A short, modified, underground stem surrounded by usually fleshy modified leaves that contain stored food for the shoot within
Corms: A short, thick, fleshy, vertical, swollen, solid underground plant stem that serves as a food storage organ. Plants use corms to survive conditions such as winter or drought. Corms have one or more internodes with a bud at the tip. Sometimes they bear external protective dry papery scale leaves. Roots grow from the base. Example: the gladiolus
Stem Tubers: Usually located near the soil surface, stem tubers from at the sides of a parent plant where they produce shoots from grow into stems and leaves while the underside develops roots. They develop from thickened rhizomes or stolons. They are used to survive winter or drought and give nutrients for regrowth in the following growing season. They are an instrument of asexual reproduction. Examples: Cyclamen, potato
Root Tubers: An enlarged, modified lateral root that acts as a food storage organ. They store nutrients over the times when the plant can’t grow and therefore ensure its survival year to year. The enlarged root can develop at the end, middle or involve the whole root which is what differs it from the stem tuber. Examples: Sweet potato, Yam, Dahlia
Stolons: Slender, creeping stems that grow either at the soil surface or below the ground and develop new plants (clones) at the tip and puts forth roots from nodes spaced at intervals along its length.
Runners: A type of stolon that exists above ground. Example: strawberries
Suckers: A secondary shoot that develops from the root or base of a woody plant. It often grows some distance from the parent plant and can be separated from the parent plant once the suckering shoots have developed their own root system.
Rhizomes: Sometimes cordlike or fleshy underground stems that grow horizontally and send out roots and shoots from the nodes. They allow asexual propagation and facilitate the plant to survive adverse conditions underground. Example: iris, ginger
Culms: The stem usually found in Monocots and the Gramineae kingdom
Sexual Reproduction
Pollination
Sterile Flowers: Cannot be fertilized
Colourful flowers and bracts: Flowers are often colourful to attract pollinators. Bracts are usually associated with the reproductive structures like a flower, inflorescence axis or cone scale. They are a modified leaf that is sometimes petal-like and colourful to also aid in attracting pollinators.
Nectar: Nectar is a sugary liquid (up to 60% sugar) that is produced in glands called nectaries. In flowers, nectar attracts pollinating animals. Nectar can also be a nutrient source to animals and provides the plant with anti-herbivore protection. Pollinators such as bees, butterflies and moths, hummingbirds and bats all consume nectar.
Scents: Evolution has caused some plants to develop strong scents to attract pollinators.
Wind Pollination: When the pollen is carried in the wind. The flowers may be small, green and not showy. They tend to produce a large volume of pollen grains and therefore this method is wasteful of a plant’s resources and is seen as a primitive and inefficient method of pollination. The stamens can have very long filaments and the styles may be large and feathery in order to trap the pollen.
Bird Pollination: Flowers that attract Hummingbirds tend to be large red/orange tubes with a lot of nectar. Tubes suit Hummingbirds as they can hover in front of them. Perching birds such as sunbirds and honeyeaters need flowers with a landing platform as they don’t like to hover. Birds do not have a strong sense of smell so the flowers they pollinate are usually odourless.
Bat Pollination: The flowers are usually large and showy. They are white/light coloured, have strong scent and open at night when bats are active. They are often large, bell-shaped and have bigger pollen than other plants. The nectar that the bat drinks is usually available for a long time. In America in particular, bat pollinated flowers will often have sulphur-scented compounds.
Non-flying animal pollination: Non-flying pollinators are mainly marsupials, primates and rodents. The flowers they pollinate are usually large and sturdy, or grouped together as multi-flowered inflorescences. Many of these animals are nocturnal so the plants often don’t have bright colours, but instead a strong odour. They will flower a lot to produce a large amount of nectar and pollen because the pollinator mammals are larger and don’t have as much precision as smaller pollinators.
Insect Pollination: Usually done by bees, butterflies, moths, flies and beetles. Plant species frequently have brightly coloured or scented flowers, nectar, or attractive shapes and patterns. The pollen grains are usually bigger than wind-pollinated plants. They usually have nutritional value to insect so they will use them for food and unknowingly spread them to other flowers.
Generalist Pollination: When a plant attracts a species that will go to many different types of flowers, not just one. The plant will also attract many different types of species. Most pollinators are generalists.
Specialist Pollination: When a pollinator animal only drinks nectar or collects pollen from a particular plant species.
Mating Systems
Self compatible: when a plant is able to fertilize itself
Self incompatible/obligate out-crossing: Self-incompatibility is the name for the genetic mechanisms in flowering plants that render it unable to self-fertilize. This in turn encourages out-crossing which is when a species introduces a new genetic material into the breeding line and causes genetic diversity. This is the most important mechanism for preventing selfing (inbreeding) and producing new genotypes in plants.
Outcross pollination: This occurs when pollen is delivered to a flower from a different plant. Plants adapted to outcross pollination usually have taller stamens than carpels or use other mechanisms to better ensure the spread of pollen to other plants' flowers.
Self pollination: When pollen from one flower pollinates the same flower or other flowers of the same plant. It has probably evolved when pollinators were not reliable for pollen transport. It’s mostly seen in short-lived annual species and plants that colonize new locations.
· Cleistogamy: Self-pollination which happens before the flower has opened. The pollen is released from the anther within the flower or the pollen on the anther grows a tube down the style to the ovules. Cleistogamous flowers are therefore required to be self-compatible.
· Geitonogamy: When a flower is pollinated with pollen from another flower on the same plant. For plants with animal pollinators, the animal does this by visiting multiple flowers on the same plant. This can also occur in wind-pollinated plants.
· Parthenocarpy: When fruit is produced naturally or artificially without fertilization of ovules. The fruit is therefore seedless. Parthenocarpy can sometimes occur as a mutation in nature, but if it affects every flower then the plant will no longer be able to sexually reproduce but might be able to propagate by vegetative means. It can be useful for plants as a defense against seed predation. It means the plant can still provide food for the seed dispersers when pollination is unsuccessful and stop them from starving or migrating.
Perfect/bisexual/hermaphrodite flowers: Flowers that have both pistils (female) and stamens (male). A majority of species have this.
Imperfect/unisexual flowers: A flowers that have either only pistils (female) or stamens (male).
Dioecy: When a plant has only unisexual flowers on it that are either all male or all female.
Monoecy: When a plant has only unisexual flowers on it and they are a mixture of male and female.
Andromonoecy: When an individual plant produces both bisexual and male flowers.
Gynomonoecy: When an individual plant produces both bisexual and female flowers.
Androdioecious: When a species has bisexual flowers on some plants and male flowers on other plants.
Gynodioecious: When a species has bisexual flowers on some plants and female only flowers on other plants.
· Protandry: A dichogamous plant where the male function comes before the female function
· Protogyny: A dichogamous plant where the female function comes before the male function
Hybridization: Natural or artificial process. When a normally self-pollinating species is hybridized by removing the anthers and then pollen is transferred from another plant. A paintbrush can be used to place the foreign pollen on the stigma.
Hybrid Swarms: When a population of hybrids have survived the initial hybrid generation, with interbreeding between hybrid individuals and backcrossing with its parent types. Such populations are highly variable. Hybrid swarms occur when the hybrid is viable and at least as vigorous as its parent types; and there are no barriers to crossbreeding between the hybrid and parent types. Swarms cannot occur if one of these conditions is not met.
Dispersal
Wind Airborne: The wind can carry seeds away from the parent in a wide area over long distances. Very light seeds can be easily blown away by the wind. Heavier seeds require features such as parachutes or wings to help keep them flying in the air.
Wind Overland: Tumbleweeds are an example of seed dispersal overland
Water Aquatic: Plants that grow near the water often require water to transport seeds. Seeds may be light in weight or contain fluff so that they float.
Water Marine: Some seeds are dispersed in the ocean. They tend to have woody, waterproof coverings so they can float in salty water for long periods.
Animals/Birds eaten: To attract animals and birds to eat the seed, the covering will tend to be brightly coloured and sweet tasting. Some seeds are collected by animals, buried and then some forgotten resulting in germination.
Animals in fur: Some seeds have fruits or individual sees covered in hooks or spines which attach to the animals fur or feathers. The animal then transports the seed and it falls or is rubbed off.
Ants: Dispersal of seeds by ants is common in many shrubs of the southern or herbs of the northern hemisphere. The seeds have an attachment that attracts ants called the elaiosome. Ants carry the seeds into their colonies, feed the elaiosome to their larvae and discard the otherwise intact seed in an underground chamber.
Human Activities: People can transport seeds usually when eating fruit. Throwing an apple core on the ground when on a picnic or hike, spitting out small seeds in grapes or watermelon, or throwing away an apricot or peach seed are examples. Humans may also get seed stuck on clothing or other external material and transport seeds until they fall or are brushed off.
Breaking of seed dormancy adaptations
Cold: Some seeds need cool soils to germinate. In many woody and in certain herbaceous species the dormancy can be broken by chilling treatments, just above freezing.
Warm: Some seeds such as cocklebur and amaranth will only germinate at high temperatures. Many seeds will germinate in early to mid summer due to the soil temperature being warm.
Wet: Some seeds require certain amounts of water saturation or drying in order to germinate.
Fire: Some seed germination can be triggered by high temperatures (as from fire) and smoke. This is particularly important after a bush fire for forest regeneration.
Light: Light sensitivity affects the germination of some seeds. The seeds need a period of darkness or light to germinate. In species with thin seed coats, light may be able to penetrate into the dormant embryo. The presence of light or the absence of light may trigger the germination process, inhibiting germination in some seeds buried too deeply or in others not buried in the soil.
Abraded/eaten: Some seeds require abrasion to the outer coating in order to break the seed dormancy. This could be from being eaten (but not digested), animal scratching or abrasion over time from weather conditions.
