Seeds & Fruits

Let's learn a bit more about seeds!  Seeds are central to the food system (and human civilization!) and are tied closely to culture and traditions.  As I'm sure you already know this makes seeds, and their potential ownership and manipulation, a heated topic.  Explore this conversation in the first part of the website.  Then move on to some basic seed anatomy and function as well as figuring out why we eat seeds and what nutrition they have for us (endosperm....yum!).  

Central Questions and Topics

1. Who should "control" seeds and why?  What are the central arguments being made?

2. What are you eating when you are eating a seed?  Think of peas, corn, beans, etc.  Think about endospermous vs non-endospermous seeds.  What about when you eat flour?  What is the difference between whole wheat and refined white flour?  How does this correspond to the parts of the seed?

3. Know the process and structures involved in seed germination.  How can humans aid in seed germination for cultivated plants?

4. Know the different types of fruits and what distinguishes them from each other.  Pay close attention to how flexible plants are at using different parts of the flower to make parts of the fruit.

Humans and Seeds - Controversies and Future

I have just posted the trailers for each of these documentaries.  I think the trailers do a pretty good job of laying out what these videos are about.  Feel free to watch the full movies - though you are not required to for class.  These serve as a nucleation point for a discussion about seeds, seed sovereignty, the resilience of our crops, our connections to food, and the future of feeding humanity when it comes to seeds!

Wheat Seed Photosynthesis - Read this short article about engineering wheat to use C4 pathway

seed anatomy and structures

Monocot seeds

These are really important when it comes to the development of human societies!  When reviewing these diagrams think about how the plant is using these different structures but also think about how humans have "hijacked" these structures for their own nutrition (and why)!  Is it nutritious for us to only eat the endosperm part?  Why or why not?

The grains of grasses are single-seed simple fruits wherein the pericarp (ovary wall) and seed coat are fused into one layer. This type of fruit is called a caryopsis. Examples include cereal grains, such as wheat, barley, and rice.

The dead pericarp of dry fruits represents an elaborated layer that is capable of storing active proteins and other substances for increasing survival rate of germinating seeds.

Whole Wheat Flour vs. White Flour

The key difference between whole wheat flour and white flour lies in how much of the wheat kernel is used during milling. This difference significantly impacts the final product's color, texture, nutritional value, and baking properties.

Breakdown of the Wheat Kernel:

• Bran: The outer layer, rich in fiber, B vitamins, and minerals. It contributes a coarse texture and nutty flavor.

• Germ: The core of the kernel, containing vitamins, minerals, healthy fats, and some protein.

• Endosperm: The starchy inner part, mainly composed of carbohydrates. It provides structure and browning in baking.

Milling Process:

• Whole Wheat Flour: Made by grinding the entire wheat kernel (bran, germ, and endosperm) together. This results in a flour with a coarser texture and a light to medium brown color.
  
  

• White Flour: Made by primarily grinding the endosperm, with some of the bran and germ removed. This creates a finer-textured flour with a bright white color.
  
  

Nutritional Differences:

• Fiber: Whole wheat flour is significantly higher in fiber than white flour. Fiber promotes gut health, regulates blood sugar, and aids in weight management.

• Micronutrients: Whole wheat flour retains more vitamins, minerals, and antioxidants naturally present in the bran and germ, which are largely removed in white flour. These include B vitamins, iron, zinc, and magnesium.

• Carbohydrates: White flour has a higher proportion of carbohydrates, mainly refined starch, which can lead to blood sugar spikes.

Baking Properties:

• Gluten Development: White flour, with its higher gluten content due to the presence of endosperm protein, is better for creating airy and elastic doughs suitable for bread and pastries.

• Flavor: Whole wheat flour adds a nutty flavor to baked goods, while white flour has a more neutral taste.

• Texture: Whole wheat flour creates a denser texture in baked goods compared to white flour.

Choosing Between Them:

• Health Benefits: Whole wheat flour is generally considered a more nutritious choice due to its higher fiber and micronutrient content.

• Culinary Use: White flour offers better gluten development for specific baked goods.

• Blending: Many bakers choose to combine whole wheat flour and white flour to achieve a balance of desired texture, flavor, and nutritional content.

eudicot seeds

These can be endospermous (like the seed below) or nonendospermous (like peas).  Nonendospermous eudicot seeds provide energy to the embryo solely from the cotyledons. 

a bit on seed germination

anatomy of fruits

Wikipedia Article here - good brief read

• Exocarp: The outermost layer of the fruit wall (pericarp), often forming the skin or rind.

• Mesocarp: The middle layer of the fruit wall, usually the fleshy and edible part in fruits like peaches and berries.

• Endocarp: The innermost layer of the fruit wall, which can be thin and membranous (like in citrus fruits) or hard and stony (like in drupes like peaches and cherries).

Fruit Categories:

• Aggregate fruits: Formed from a single compound flower with many ovaries. Examples: raspberries, blackberries.

• Multiple fruits: Formed from the fused ovaries of multiple flowers. Examples: figs, mulberries, pineapples.

• Simple fruits: Formed from a single ovary, may contain one or many seeds. Can be fleshy or dry.

Simple Fruit Types (Fleshy):

• Berries: Entire pericarp (fruit wall) is fleshy, excluding the skin-like exocarp. Examples: grapes, tomatoes, cucumbers.

  1. 1. • • A hesperidium is a type of berry with a leathery rind and juicy pulp inside.

            • Key characteristics:

• Modified berry: It's considered a special subtype of berry due to its unique structure.

• Leathery rind: The outer skin is tough and often contains oils.

• Juicy pulp: The inside is divided into segments filled with fluid-filled sacs (juice vesicles).

• Citrus family: Hesperidia are most common in citrus fruits like oranges, lemons, limes, and grapefruits.

• A pepo is a type of berry with a hard rind. It is the characteristic fruit of the gourd family (Cucurbitaceae).

  • Examples of pepos include:

• Watermelon, Cantaloupe, Honeydew melon, Cucumber, Squash, Pumpkin, Zucchini

• 1. 1. • Key characteristics:

          • • • Modified berry: A pepo is a specific type of berry, but with a hard, thick rind.

              • Hard rind: The exocarp (outer skin) of a pepo is thick and tough.

              • Fleshy interior: The mesocarp (middle layer) is typically the fleshy, edible part of the fruit.

              • Many seeds: Pepos usually contain numerous seeds embedded in the fleshy interior.

• Pomes: Fleshy part develops from the floral tube, most of the pericarp is fleshy, but the endocarp is cartilaginous. Example: apples.

• Drupes: One-seeded with a fleshy mesocarp and a stone-like endocarp. Example: peaches.

Simple Fruit Types (Dry):

• Achenes: Small, dry, one-seeded fruits with a thin pericarp. Example: sunflower seeds.

• Capsules: Dry fruits that split open to release seeds. Examples: sweet peas, soybeans.

• Follicles: Dry, single-carpel fruits that split along one seam. Example: milkweed.

• Nuts: Hard-shelled, dry fruits that do not split open. Examples: hazelnuts, acorns.

Other Fruit Terms:

• Accessory fruit: Edible portion derived from tissues other than the ovary. Example: strawberries (receptacle).

• Caryopsis: Single-seeded fruit with a fused pericarp and seed coat. Examples: cereal grains like wheat, barley, rice.

Fruit Evolution:

• Fleshy fruits likely evolved from dry fruits.

• Fruit diversity is a result of selection for advantageous seed protection and dispersal in different environments.

• Animal dispersal of fleshy fruits is common and efficient but doesn't necessarily increase dispersal distances.

IN PARAGRAPH FORM:

Fruits are found in three main anatomical categories: aggregate fruits, multiple fruits, and simple fruits. Aggregate fruits are formed from a single compound flower and contain many ovaries or fruitlets.[3] Examples include raspberries and blackberries. Multiple fruits are formed from the fused ovaries of multiple flowers or inflorescence.[3] An example of multiple fruits are the fig, mulberry, and the pineapple.[3] Simple fruits are formed from a single ovary and may contain one or many seeds. They can be either fleshy or dry.  The types of fleshy fruits are berries, pomes, and drupes. There are berries that are known as pepo, a type of berry with an inseparable rind, or hesperidium, which has a separable rind.[4] An example of a pepo is the cucumber and a lemon would be an example of a hesperidium.  An apple is an example of a pome.  An example of a drupe would be the peach.

You can combine the terms for fruit structure (aggregate, multiple, simple) with those for fruit type (berries, pomes, drupes).  For example - raspberries are actually aggregate drupes, mulberries = multiple drupes.

other resources....

Great in-depth website - https://www2.palomar.edu/users/warmstrong/termfr4.htm

Flower Anatomy predicts fruit anatomy - http://fruitandnuteducation.ucdavis.edu/generaltopics/AnatomyPollination/Fruit_Anatomy/