Term 2 – Week 1 & 2 – Plant Science

seedling

The first two weeks of term 2 have been focused on Plant Science (botany). It is essential to have knowledge around the basic structure of plants and the processes within plants (like photosynthesis) to help understand some practical things, such as grafting, wilting plants, pollination, seed production and pruning.

We started off going right back to basics and looking at the smallest part of plants – cells!

cell

Plant cells are a bit different to human or animals cells but share many of the same features; nucleus containing hereditary material and mitochondria as the power house of the cell. Plant cells have a cell wall that covers the cell with cellulose that is semi-permeable allowing the movement of dissolved minerals. They also have a vacuole that holds water and minerals in a membrane that is separate from the cytoplasm and supports the shape of the cell.

We also covered stems, leaves, roots and flowers.

Stems and roots have areas called meristems, which is where cells divide and the plant grows. Meristems are found in the tips of shoots and roots (apical meristem) and around the outside of a trunk or branch (lateral meristem or vascular cambium). When you are grafting two plants together it is the vascular cambium regions that need to be joined for a connection to be made.

stem

Cross section of a woody dicotyledon stem

The stem also contains the xylem and phloem. The xylem moves water and minerals from the roots up throughout the plant. The phloem moves sugars and nutrients made by photosynthesis and respiration down throughout the plant.

Roots help stabilise the plant, take up water and dissolved minerals and nutrients from the soil and can also act as storage tissue for energy for the plant. Rhizomes, bulbs, corms and tubers are examples of storage tissues.

leaf2

Leaves are the main part of the plant where photosynthesis happens. There are tiny pores (called stomata), usually on the underside of the leaf, that open and close to allow gas exchange. The veins you can sometimes see on a leaf if you look closely, are made up of vascular bundles that consist of xylem and phloem cells.

leaf

Flowers are the seed bearing part of a plant. They are where pollination happens and fruit forms.

flower

Plants can have flowers that are “complete”, meaning the flower has both male and female parts (roses, plums); monoecious, separate male and female flowers on the same plant (pumpkins, zucchini) or dioecious, separate male and female plants (kiwifruit, ginkgo). This affects how the plant pollinates, either self pollinating or cross pollinating.

There is a lot more involved in plant science, this is just a few basics that barely scratch the surface. I find diagrams make it easier understand and to get my head around all of the terminology.

Last couple of week’s weather – winter is on the way:

week2

week2

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