Introduction

Fruits and seeds form both the bulk of agricultural commerce and are common contaminants, which if introduced and colonize may lead to devastating consequences to crops and wildlands. Other plant parts that are vegetative in origin may also be contaminants, some of which if introduced to an amenable environment can grow and produce plantlets. However, those are not the focus of this tool. To learn more about vegetative propagules, see this description in the FNWD tool. Determining if a specimen is a fruit or a seed is not always straightforward, especially if only fragments are found. Although this tool was designed for that potential ambiguity, understanding fruit and seed morphology and how they might appear as contaminants will aid in interpreting the information in the fact sheets and identifying a specimen.

Plants that reproduce using seeds are classified into over 400 families and can either be flowering (angiosperms) or non-flowering (gymnosperms). A seed includes an embryo that is often surrounded by nutritive tissue (endosperm) and encased in and protected by an outer coat, the seed coat or testa. In angiosperms, the seed is protected to varying extents by the fruit wall (pericarp), which develops from the ovary wall. Seed coat and fruit wall modifications, which primarily function to aid in dispersal, can provide clues to their identity.

Illustrations and photos used in the figures below and on the other "About fruits and seeds" pages are not to scale.

Longitudinal section of seed showing the seed coat, nutritive tissue, and embryo.
Longitudinal section of seed showing the seed coat, nutritive tissue, and embryo.
Ovary or immature fruit in longitudinal section with ovary wall highlighted in green (left); fruit in transection with fruit wall (derived from ovary wall) highlighted in green (middle); whole fruit (right)./>
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Ovary or immature fruit in longitudinal section with ovary wall highlighted in green (left); fruit in transection with fruit wall (derived from ovary wall) highlighted in green (middle); whole fruit (right).
About fruits and seeds