Lydia - Items #21-25

LICHEN

Lichens are really cool organisms. They are composed of a fungus that is in a symbiotic relationship with a photosynthetic partner, usually some type of green algae. The composite organism is usually found on tree trunks or rocks, and looks like a crusty coating that can sometimes be branching. Lichen can survive in very extreme climates such as the arctic, deserts, or rocky coasts. Yet lichen is also found in rainforests, and other mild temperate climates on Earth.

MODIFIED LEAF OF A PLANT

The pea plant has a great example of a modified leaf of a plant. The tendrils that it uses to attach to other structures (or in this case itself…not very helpful) help it to climb towards the light in an otherwise difficult area. This adaptation also allows the plant to use more of its energy towards producing fruit rather than building strong stalks for support.

PHLOEM

Phloem is the living tissue that carries nutrients (sap) to the part of the plant where it is needed. It transports nutrients from the tips of the tree all the way down to the roots (transportation in the downwards direction). In this picture, the phloem is the thin dark grey-blue ring near the outside of the cross section. It is the inner most layer of the bark of a tree. 

POLLEN

Pollen, in angiosperms such as this lily, is found on the tip of the stamen (the anther). Pollen grains are hard protective shells that contain sperm (male gamete). Wind, water, and animals can act as transportation for the pollen grains to the stigma of the carpel of another flower of the same species. Once the pollen lands on the stigma, it germinates and produces a pollen tube which grows down the style until it reaches the ovary and releases the sperm inside, fertilizing the ovules.

SEED DISPERSAL (WIND)

These Norway maple seeds (affectionately known as helicopters to many) have fallen from the tree nearby. When the wind catches them, they will be blown to other places and hopefully become buried in the soil. If everything goes as planned, the seeds will sprout next spring and produce their own baby maples! Plants have limited mobility as they can’t simply get up and walk away like animals can, so seed dispersal aids the plants in transporting seeds away from the parent. The farther away from the parent the seed lands, the more likely it will survive because it won’t be required to compete with the parent for resources.