“Though I do not believe that a plant will spring up where no seed has been, I have great faith in a seed. Convince me that you have a seed there, and I am prepared to expect wonders.”
- Henry David Thoreau (1817 – 1862)
Next time you bite into an apple, or eat a peanut, think about the evolutionary genius behind them. Without fruits and nuts, plant life would not be able to persist. Just as humans and other animals reproduce, so do organisms of the plant kingdom. Their method of reproduction is not much different than our own, but includes the faithful seed.
Technically speaking, seeds are the end result of sexual reproduction by plants. Plants can be divided into two different groups called the angiosperms and gymnosperms. These groups of plants can be distinguished by their different methods of seed production. Angiosperms are the flowering plants that produce fruit such as an apple with one or more seeds. They make up about 80 percent of all plant species. On the other hand, the gymnosperms, which include conifers, do not produce fruit to protect the seeds. The seeds of gymnosperms are “naked” and are contained within a woody cone.
Seeds are usually comprised of three parts: the embryo, nutrients to support the embryo, and a seed coat. Once optimal conditions arise such as warmer temperatures or increased availability of water, a seed begins to germinate. Germination is the process by which a seed begins to grow and a new plant emerges. If conditions are not optimal, seeds will remain dormant or inactive. Dormancy can be caused by reactions within a seed or by outside influences such as the availability of water or sunlight. Seeds ability to remain dormant is a very important adaptation. Dormancy prevents the seeds from germinating when conditions are not optimal and also can ensure that not all individual offspring germinate at the same time. Some seeds in a batch will remain dormant while others germinate. If a catastrophic event such as a late frost was to occur, not all offspring would be destroyed.
The main goal of all organisms, including plants, is to reproduce. In order to ensure reproduction, plants must be able to ensure that their seeds or offspring find favorable conditions to grow and produce more seeds. Plants have evolved many different and interesting means of insuring that their offspring will survive by developing many dispersal methods for their seeds. Dispersal can be broken down into three different categories: wind, water, and animal dispersal mechanisms.
Wind is a very common means of dispersal for seeds. The most well know plant that uses this method is the dandelion whose tiny seeds spread effortlessly and are made of tiny hairs that aid in transport. Another example is the maple tree samaras or “whirly-gigs” which glide from the trees every spring in the North East. Wind dispersal is often used by plants that produce fruit which is dehiscent. This means that the seeds are contained within some sort of a pod which eventually matures and opens to release the seeds. An example of this would be the seeds of the milkweed. On the contrary, some seeds are indehiscent, and do not come from a mature seed pod. These indehiscent seeds usually fall from a tree like an acorn.
Although not common, water is sometimes a means of seed dispersal. Seeds that are dispersed by means of water must be equipped for the journey. Without water resistance seeds could rot. Seeds usually have a hard outer shell that can fight water damage. The seeds can be transported by rivers or by sea water and must be highly buoyant to survive. Examples of seeds that are transported by water are the coconut and other types of tropical plants who’s seeds can travel hundreds of miles by means of ocean currents.
Fruit produced by trees such as apples, or even acorns, are key to animal or biological seed dispersal. Tasty fruits are made to entice an animal to consume them. Seeds within the fruit are not digested by the animal and pass through the digestive tract only to be deposited in some other location. Oaks trees which produce acorns in the fall rely on rodents or birds to disperse their seeds. Acorns are the hard-shelled “fruit” of the oak tree and contain a tiny seed within them. Not all the acorns a squirrel or other animal buries in the fall will be recovered, thus the remaining acorns will grown into new oak trees capable of continuing the process of seed dispersal once they mature.
Seeds are an important food source for several species of animals. They contain high levels of fats and nutrients that are important for over wintering in the Northeast. Since seeds and their fruits contain all the nutrients needed to produce new plant life, it is no surprise that eating seeds can also be beneficial to people. Many of the seeds we eat are high in vitamins and out of all the plant products have the highest content of iron and zinc. The majority of the calories we consume on a daily basis come from seeds like legumes, cereal, and nuts. Although these seeds are healthy, there are several other types of seeds that are beneficial to our diets. Below are a few alternative seed recipes that are both delicious and healthy.
Roasted Pumpkin Seeds
- 1 1/2 cups raw whole pumpkin seeds
- 2 teaspoons butter, melted
- 1 pinch salt
- Preheat oven to 300 degrees F (150 degrees C).
- Toss seeds in a bowl with the melted butter and salt.
- Spread the seeds in a single layer on a baking sheet and bake for about 45 minutes or until golden brown; stir occasionally.
Broccoli Salad With Sunflower Seeds
- 1 Head Fresh Broccoli, Cut Into Pieces
- 1/4 Cup Red Onions, Chopped
- 1/2 Cup Golden Raisins
- 3 Tbs White Wine Vinegar
- 2 Tbs White Sugar
- 1 Cup Light Mayonnaise
- 1 Cup Sunflower Seeds
- In a medium bowl, combine the broccoli, onion and raisins.
- In a container with a tight lid, add the vinegar, sugar and mayonnaise, seal, and then shake until the ingredients are blended.
- Pour over the broccoli mixture, and toss until well mixed.
- Refrigerate for at least two hours.
- Before serving, toss salad sunflower seeds.
Hummus with Pine Nuts (seeds from a pine cone)
- 2 garlic cloves
- 1/2 tsp salt
- 1 can garbonzo beans, thoroughly rinsed
- 1/3 cup tahini
- 1/2 of a juicy lemon’s worth of lemon juice
- 2 tbs olive oil
- 1/2 cup water that’s not from the can!
- One handful fresh parsley
- 2 tbs olive oil
- 2 tbs pine nuts
- In a blender or food processor, combine garlic, beans, sesame paste, lemon, 2 tbs oil, water, and salt, and blend thoroughly.
- Add salt to taste and water to smooth the texture.
- Pour the hummus into a serving dish, rinse the blender, and throw in the parsley and 2 tbs oil. Puree thoroughly until you have a green colored olive oil.
- Toast the pine nuts in a dry (no oil) pan until they turn lightly brown.
- Set them aside to cool.
- Sprinkle olive oil and pine nuts on top of the hummus just before serving.
- Palmer, Laurence E.Fieldbook of Natural History: Second Edition.New York: McGraw-Hill Book Company, 1975.
- All recipes collected from Foodnetwork.com