Seeds are very variable in structure, so much so, that scarcely any two seeds have a similar structure. It is necessary, therefore, when examining seeds, to compare the structure of the seed under examination with authentic plates or with the section of a genuine seed. The layers of the seed are the spermoderm, perisperm, endosperm, and embryo. In some seeds the spermoderm forms the greater part of the seed; in others the perisperm is greatest in amount; in still others the cotyledons make up most of the seed, as in the mustards. The cells forming these different layers differ in form, structure, and number; therefore it is not difficult to distinguish and to differentiate between the different seeds when viewed as a section or as a powder. Almond is studied because it has most of the layers and cells found in seeds.
SPERMODERM The spermoderm is the thin, brown, granular-appearing skin of the almond. The layers of the spermoderm are the epidermis, the hypoderm, the middle layers, and the inner epidermis.<Callout type="tip" title="Tip">Almond's structure makes it a good model for understanding seed anatomy.</Callout>
The epidermis consists of radially elongated, thick-walled stone cells which occur alone or in groups of two or more, but seldom as a continuous layer. The upper or outer part of the stone cells is non-porous, but the inner walls are strongly porous (Plate 123, Fig. i).
The hypoderm. The cells forming the hypoderm are compressed, the wall structure is practically indistinguishable, and the whole mass is reddish brown (Plate 123, Fig. 2). Occurring in this brown layer are several vascular bundles (Plate 123, Fig. 3).
The middle layers. The cells forming the middle layers (Fig. 4) have thin, wavy, light-colored walls which are frequently compressed, and it is with much difficulty that their outlines are made out.
The inner epidermis. The cells forming the inner epidermis are rectangular in form, and they contain reddish-brown cell contents (Plate 123, Fig. 5).
ENDOSPERM The endosperm. The cells forming the endosperm are large, rectangular in outline, usually one layer thick, and they contain aleurone grains.
EMBRYO The embryo. The cells forming the outer layer of the embryo are smaller than the inner layers, and they are immediately inward from the layer of endosperm cells (Plate 123, Fig. 7).<Callout type="important" title="Important">The embryo is crucial for germination.</Callout>
The cells forming the greater part of the embryo are large, rounded, and they contain aleurone grains and fixed oil (Plate 123, Fig. 8).
In white and black mustard are characteristic mucilage and palisade cells.
In nux vomica, stropanthus, and St. Ignatius's bean are characteristic hairs.<Callout type="warning" title="Warning">Be cautious of toxic seeds like nux vomica.</Callout>
In physostigma and kola are characteristic starch grains.
In henbane, capsicum, stramonium, lobelia, and belladonna seeds are characteristic epidermal cells.<Callout type="beginner" title="Beginner">These seeds can be dangerous due to their toxic properties.</Callout>
In areca nut, colchicum, saw palmetto, and nux vomica are characteristic thick-walled, reserve cellulose cells.
In cardamon seed are aggregate starch masses with irregular outlines.
In bitter and sweet almond, linseed, pepo, and stropanthus are aleurone grains.<Callout type="gear" title="Gear">A microscope is essential for examining these structures.</Callout>
In bitter and sweet almonds are stone cells.
In linseed, quince seed, and in white and black mustard are epidermal cells with mucilaginous walls and contents, etc.
Key Takeaways
- Almonds have a complex structure that includes spermoderm, perisperm, endosperm, and embryo layers.
- The embryo is crucial for germination and contains aleurone grains and fixed oil.
- Some seeds contain toxic components like nux vomica or henbane.
Practical Tips
- Use a microscope to examine the detailed structure of seeds for accurate identification.
- Understand that different seeds have unique characteristics, which can be useful in survival situations.
- Be cautious when handling potentially toxic seeds and always wear protective gear.
Warnings & Risks
- Some seeds like nux vomica are highly toxic and should not be ingested without proper knowledge.
- Misidentifying a seed could lead to serious health risks, so thorough examination is crucial.
- Handling seeds with mucilaginous walls can cause skin irritation; wear gloves when necessary.
Modern Application
While the detailed microscopic analysis of seeds as described in this chapter may not be immediately applicable in modern survival scenarios, understanding seed structure and composition remains valuable. Modern tools like portable microscopes and digital identification apps make it easier to identify seeds accurately. This knowledge can help in foraging, emergency food sources, or even creating a sustainable garden in challenging conditions.
Frequently Asked Questions
Q: What is the spermoderm of an almond seed?
The spermoderm is the thin, brown, granular-appearing skin of the almond. It consists of layers such as epidermis, hypoderm, middle layers, and inner epidermis.
Q: What are aleurone grains found in seeds like almonds?
Aleurone grains are large, rectangular cells containing nutrients that are usually one layer thick. They are a key component of the endosperm in many seeds.
Q: Why is it important to compare the structure of a seed with authentic plates or sections?
Comparing the structure of a seed under examination with authentic plates or sections helps ensure accurate identification and differentiation between different seeds, which is crucial for their proper use in survival scenarios.