The cotyledon, which forms in the embryo of a seed before germination, stores food for the embryo. Along with the endosperm, the cotyledon nourishes the new growth of the plant. It is the part of the seed that emerges from the testa, or hard covering, during germination. It sometimes grows upward, turning into a set of leaves as the seed germinates, using photosynthesis to nourish the newly forming plant further.
The leaves formed by the cotyledon sometimes drop off as the plant's first real leaves, which look different from the leaves formed by the cotyledon, emerge. Other times, they remain a part of the plant for years. A cotyledon may also remain underground rather than shooting up as a set of leaves, where it functions as a storage area for food for the plant.
Seeds can have one cotyledon or a pair of cotyledons. Those with one are called monocots, while those with two are classified as dicots. Seeds that are dicots have cotyledons that function as leaves, while monocots have cotyledons that are appendages for food storage. Seeds that store their food in cotyledons inside the embryo are called exalbuminous. Seeds can remain in a dormant state for years, only germinating when conditions are right.Learn More
The seed germination process is a complex process in which the embryonic plant created by sexual reproduction of plants propagates the species by forming a new, independent plant. In order to germinate, the moisture and temperatures must be right. New plants live a short while on the sugars stored in the seed, requiring the plant to start gathering nutrients and moisture from the soil and producing its own food quickly.Full Answer >
High concentrations of salt in soil generally reduce the rate of seed germination. Increased salt levels prevent essential water from seeping into the seed. The lack of moisture retards its growth and development, which may cause the seed to wilt and eventually die.Full Answer >
Monocot leaves have veins that are parallel, have leaves that are in groups of three, have one cotyledon and have scattered vascular bundles. They are one type of a leaf with the majority of other leaves being dicot leaves.Full Answer >
In hypogeal germination, cotyledons remain inside the seed shell, beneath the ground and non-photosynthetic, while in epigeal germination, the cotyledons expand to split the seed coat, allowing the sprout to push them above the ground where they become photosynthetic, according to Reference.com. Epigeal germination allows the young plants to begin providing food quickly as the cotyledons have little food stored to provide for their needs.Full Answer >