Seed adaptations Flashcards

Question

What are germination triggers?

Answer 1

Two elements that trigger germination are cold and fire.

Answer 2

Going through a cold spell very often triggers germination. As the seed warms up after that cold spell, it will know spring has arrived and it is safe to grow

Answer 3

Fire clears land of competition and creates a sterile seedbed for plants to grow. many species in fire prone areas produce seed that will only germinate after fire when growing conditions are good, you will then have a mass germination after a fire.

Answer 4

seeds that are held back from germination Cold can produce this effect Some species which are eaten particularly by birds will only germinate well after they have been through the digestive tract of a bird (can take years to germinate) Fire (clears area from competition)

Answer 5

SMOKE. the chemicals in smoke facilitate germination.

Answer 6

seed which is buried in the soil. Mostly short lived species. That seed will very often live for decades. Disturb the soil and the seeds in the seed bank will start to germinate. Can be an issue and you may need to disturb the soil a few times to get the seeds to germinate and then remove.

Answer 7

Related to the life cycle and level to which the plant needs to grow and develop in the first year.

Answer 8

ANNUALS: short lived plants. Seeds germinate quickly, uniformly and easily. Usually long lived seed that waits for good condition in soil Annuals only need to grow a big enough plant to flower an seeds to keep the species going. EX: Digitalis purpurea PERENNIALS: Need to lay down reserves and build bigger root system in the first year. Woody growth is slow, so slow growth and seedlings vulnerable. May be killed by first frost so STAGGERED germination to reduce risk of death. Some perennials that produce seeds in summer can germinate from fresh seeds and can survive winter.

Answer 9

Use fresh seeds, as soon as mature on the plant. Seeds deteriorate over time.

Answer 10

Varies in how much seed they produce and the size of the seed. Either vast quantity of small seeds (with little reserves) OR smaller quantity of larger seeds (store considerable quantity of nutrients - better start in life)

Answer 11

Evolved to disseminate the seed. Prefer not to stay in one place so spread as well as possible. Digitalis: seed capsules on tall stems. Allium: Seed just falls out Asclepias incarnata: 'fly away' seed Quercus: Large seeds full of reserves for 1st year food source...short lived (3 month viability).

Answer 12

Hard seeds done to slow down and stagger germination as water takes time to penetrate coat. 1. Drop in just boiled water. 2. Chip coast with knife Grind with sand paper.

Answer 13

1. Reproduction of good plants. 2. Ensures genetic diversity 3. Preserves heritage varieties

Answer 14

Helps in collection of seed at the right time. Understanding the appropriate storage for long term preservation Awareness of plants and survival in the seed bank - important for ground preparation Self seeding can be attractive (esp. in dynamic ecological schemes - but can be invasive)

Answer 15

Heavy mulch Dense planting Awareness important to prevent issues like becoming invasive - esp wildland areas.

Answer 16

1. Know plant lifecycles and habits. 2. Understand sowing time (esp whether fresh seed or storing) 3. How to break dormancy

Answer 17

Dispersal Dormancy mechanisms Range or adaptations and advantages Benefits of adaptation

Answer 18

a. WIND: Small seeds with fluff to help spread the seeds far and wide. Taraxacum officinale. b. SPRING MECHANISM: Seeds that suddenly snap disseminating seeds up to 1.5 metres away. Geranium sanguineum c. BURRS DISPERSAL: Seeds that are designed to cling on to animal fur, which can carry the seed very far away from the parent. Arctium lappa MODEL: seed in edible berries, to be eaten and dispersed by birds – rowan, Sorbus aucuparia spring mechanism – Geranium phaeum small seed with fluff to float away on wind – dandelion, Taraxacum officinale

Answer 19

a. STRATIFICATION: The process of pre-treating a seed in order to simulate the natural conditions that would help break dormancy and allow the seed to germinate. An example would be a period of cold, as in putting the seeds in the refrigerator to simulate winter conditions. Example: Fraxinus excelsior b. SCARIFICATION: The process of opening up the seed for the movement of water or oxygen as the seed coats prevent or limits germination this way. An example would be chipping the seed to allow the water or oxygen to enter the seed and begin germination. Legumes, especially the Fabaceae family and Lathryus odoratus. MODEL: These are both ways of dealing with seed which is slow to germinate. In stratification, the seed is left outside and exposed to all weathers; cool temperatures will often stimulate germination, or more usually warm, followed by cool; it can also be done artificially in a refrigerator. Scarification is a physical process of wearing away part of the seed coat with, for e.g. sandpaper, to make it easier for water to penetrate and start the germination process.

Answer 20

a. ORTHODOX: Seeds that can be dried and stored in a cool environment, usually 5C for many years. Place seeds in a paper bag with silica gel in an airtight container. Most annuals are orthodox seeds. EXAMPLE: Legumes, such as the Fabiaceae family. b. RECALCITRANT: Recalcitrant seeds have high levels of moisture or oils and cannot be stored for long, and definitely cannot be dried. They can be sown when fresh only. EXAMPLE: Aesculus hippocastanum MODEL Orthodox seed is dry, and needs to be stored in cool dry conditions. Very often it will remain viable for many years, e.g. carrot, Daucus carota. Recalcitrant seed is moist or oily and cannot be stored long-term. For shortterm storage it needs to be kept cool and moist, e.g. English oak, Quercus robur

Answer 21

a. LARGE SEEDS: These seeds store a considerable amount of nutrients to help them through their first year of life. b. SMALL SEEDS: These seeds will have a minimal amount of nutrient reserves. c. As most plants need stratification (cold temperatures to germinate) I would plant the large seeds in late summer so they can experience the cold temperatures of winter. This will give them the warm temps of summer, cold temps of winter followed by the warming temps of spring and will break dormancy naturally. They also have a good amount of nutrients to see them through the cold temperatures. d. Not knowing what the very small seeds are, I would be hesitant to plant them in late summer. They do not have the nutrients to see them through a cold winter. I would most likely sow the seeds in trays, cover them for the natural greenhouse effect and watch them carefully. When they germinate, I will remove the cover and continue to watch carefully. As the seeds may be of a slow growing plant, I would wait up to 2 years and watch carefully. Some plants spend the first year growing roots and the second year grow above ground. After two years, with no results I would feel comfortable discarding them. MODEL Many hardy plants need stratification, therefore I would sow most of them immediately, so that they could experience warm and then cold conditions. The only ones I would not sow immediately, would be the very small ones, as these rarely need stratification; these I would sow in spring, as the weather begins to warm up. I would sow into seed trays, enclose in a clear plastic bag and leave the seed trays in a lightly shaded place. I would inspect regularly and twice a week in spring, and take out of the bag as soon as germination is seen. I would not discard trays of ungerminated seed for two years.

Answer 22

a. A SEED BANK is the seed buried in the soil which is waiting for the day when conditions are right to germinate. b. IMPLICATIONS: When creating a new area in the garden, disturbing the soil will bring the seeds to the surface allowing the right conditions for germination. This will produce a plethora of weeds and plants that need to be removed. Hoeing the area will be important and waiting to see if that has produced more weeds. You may need to hoe a few times to remove all the plants that have germinated. c. Once you have exhausted the weed germination, adding a layer of heavy mulch will help to stop more germination of seeds as the light will be reduced/eliminated by the mulch, usually about 10cm thick. d. Regarding biodiversity, some weeds are good for pollinators so perhaps accepting some weeds in the garden is a good idea, especially weeds such as Taraxacum officinale. The more variety of plants the better for biodiversity. MODEL: The 'seed bank' refers to buried seed in the soil, mostly short-lived arable weeds, which have adapted to survive through seed rather than plants. Seed remains dormant until the soil is disturbed, light often stimulating germination. The seed bank creates problems when a new area is developed for planting as there is often a mass germination of weeds which will compete with the new plants, sometimes very severely. Soil can be cleaned of its seed bank if there is time. Soil can be rotovated, and after germination of weed seeds, the whole area hoed or treated with herbicide to kill weed seedlings, then rotovated again to a depth of 10cms, the next crop of seedlings removed, and so on until the seed bank is almost exhausted. If there is no time to do this, then new plants should be surrounded with a 5- 7cms layer of coarse mulch to suppress weed seed germination, along with regular weeding.

Seed adaptations Flashcards

(46 cards)