The Seed is Planted - What's Next?
Blooms on the Horizon: Seeds Ready to Sprout
When the seed falls to a favorable location, it begins to germinate and sprout a new plant.
The seed covers a young seedling with its seed coat. Inside the seed are the embryo and food reserves.
Oxygen and water enter the seed through the micropyle, the Sun heats the soil, then the embryo sprouts and forms the root and shoot from the seed.
Germination Factors
Learn MoreThe main factors determining seed germination are water, oxygen, light, temperature, and available space.
Learn in EnglishTypes of Seed-Producing Plants:
Seed-producing plants store food for the new plant in various ways. They also differ in how the new plant emerges from the seed.
Types of Seeds
Learn MoreTwo main types of seed-producing plants are dicotyledonous (dicot) and monocotyledonous (monocot). Here are some examples:
- Dicot: Kahikatea, Kauri, Harakeke, Nīkau, Kōwhai, and Tītoki.
- Monocot: Grasses like corn, wheat, and rice.
Rights:
What Types of Seeds Exist?
Each type of seed-producing plant stores food for the new plant differently. They also differ in how the new plant emerges from the seed during germination.
Seed Types
Learn MoreDicotyledonous (dicot) seeds have two cotyledons that function as the primary food reserve, while monocotyledonous (monocot) seeds have a single cotyledon. In some monocot seeds like peas, the cotyledon may remain below ground during germination.
Germination of dicot seeds involves the cotyledons unfolding and emerging above the soil to form the first leaves. In contrast, monocot seeds have a protective covering called the coleoptile, which shields the new plant's first leaf until it reaches sunlight.
The food storage organ for most monocot seeds is the endosperm. This tissue forms during fertilization and contains nutrients that are essential for the growth of the new plant.
Germination Mechanisms
Learn MoreThe primary difference between dicot and monocot seeds lies in their germination mechanisms:
- Dicot Seeds: These seeds have two embryonic leaves called cotyledons. When the seed germinates, the cotyledons unfold and emerge above the soil to form the first leaves. They photosynthesize to provide energy and nutrients for the developing seedling.
- Monocot Seeds: These seeds have a single embryonic leaf called a cotyledon. During germination, the cotyledon remains below the soil surface, and a protective covering called the coleoptile emerges and grows above the soil. The coleoptile eventually disintegrates, allowing the first leaf to expand and photosynthesize when exposed to sunlight.
Insights: During germination, the endosperm in monocot seeds breaks down, releasing essential nutrients for the developing embryo. In comparison, the cotyledons of dicot seeds also serve as nutrient storage and can supply nutrients to the seedling before the root system becomes fully established.
Rights:
Germination of Different Seeds
Dicotyledon Seeds
Dicot seeds exhibit embryos with two cotyledons as the primary food reserve. When the seed germinates, the roots and shoot emerge from the seed coat, and the cotyledons unfold to form the first leaves. In some dicots like peas, the cotyledons remain below ground during the germination process.
Monocotyledon Seeds:
Monocot seeds have a single cotyledon acting as the food reserve. During germination, the cotyledon remains below the soil surface, and the new shoot emerges from the seed within a protective covering called the coleoptile. The coleoptile eventually disintegrates, allowing the first leaf to expand when exposed to sunlight.
Coleoptiles and Endosperm
Learn MoreColeoptiles protect the emerging shoot in monocot seeds, serving as a barrier against environmental stressors. The endosperm is the primary food storage organ in most monocot seeds. It is a tissue that forms during fertilization and has three sets of chromosomes – one from the mother plant, one from the pollen parent, and a unique set that results from fusion during fertilization.
Insights: During growth, the endosperm breaks down, liberating necessary nutrients for the developing embryo. Some monocot species utilize the endosperm during germination, while others rely on the cotyledon or reserve materials inside the kernel.
Difference Between Conifer Seeds and Others
Differeece
Differences between conifer seeds and those of other plants include their storage mechanism, size, and germination process.
Conifer Seeds
Conifer seeds typically store their food reserves in an embryo called the gametophyte. They germinate with a single cotyledon, and about 20 or more seeds may be present within a conifer cone. The germinating seed will produce a shoot and root without a Coleoptile.
In some conifer species like pines, the cones take several years to mature and release seeds. After this process, the seed may require additional stages of development before it can germinate and grow.
Insights: Conifer seeds primarily rely on photosynthesis for energy during their growing stages. They are common in colder climates, as their hard exterior protects them from harsh winter conditions.
Conifer Trees: Examples and Germination
Learn MoreKahikatea, Matai, Rimu, Miro, and Tōtara are examples of conifer trees that can be found in New Zealand. Conifer seeds may germinate from the ground or be spread throughout the forest by birds. The seedlings will start growing in early spring or after a fire, when light reaches the seeds.
Germination of Corn, Wheat, and Rice
Learn MoreMonocot seeds of corn, wheat, and rice have a growth pattern that involves the coleoptile, endosperm, and a single cotyledon. During germination, the coleoptile protects the newly-germinated shoot, pushing it through the soil and exposing it to sunlight. The endosperm serves as a primary food supply for the growing seedling.
Insights: Corn, wheat, and rice are important food crops worldwide. The unique germination characteristics of monocot seeds play a critical role in their agricultural production.
Collect, Observe, and Plant Kōwhai Seeds
Click here to download a resource on collecting, observing, and planting Kōwhai seeds. You may adapt this resource for your classroom needs.
Further Resources
To explore more about New Zealand native plants and seeds, visit these useful links:
- Seeds and Spores – Introduction: https://www.teara.govt.nz/en/plants/page-6
- Student-led Investigations on Seeds: https://www.sciencelearninghub.org.nz/resources/2113-plants
- Seed Dispersal: https://www.nzgardener.co.nz/articles/guide-to-plant-propagation/seed-propagation/
AcknowledgementsWe thank Mokoro Gillett (Principal, Te Wharekura o Te Rau Aroha) and Norman Mason (Manaki Whenua – Landcare Research) for their contributions.
The science behind environmental-science reveals that seed-producing plants like Kahikatea, Kauri, Harakeke, Nīkau, Kōwhai, and Tītoki, store food for new plants differently, with some having two cotyledons (dicot) and others having a single cotyledon (monocot). Some examples of monocot plants include grains like corn, wheat, and rice. In the lifestyle and home-and-garden sectors, knowledge of different seed types and their germination mechanisms can be beneficial when caring for various plant species. Additionally, understanding the unique germination processes of conifer seeds can provide valuable insights into the growth patterns of trees such as Kahikatea, Matai, Rimu, Miro, and Tōtara.
