Hilum (biology)
{{Short description|Structure on a seed or spore coat}}
In botany, a hilum (pronounced {{IPAc-en|ˈ|h|aɪ|l|ə|m}}) is a scar or mark left on a seed coat by the former attachment to the ovary wall or to the funiculus (which in turn attaches to the ovary wall). On a bean seed, the hilum is called the "eye".
For some species of fungus, the hilum is the microscopic indentation left on a spore when it separates from the sterigma of the basidium.{{cite book |vauthors=Kirk PM, Cannon PF, Minter DW, Stalpers JA |title=Dictionary of the Fungi |edition=10th |publisher=CABI |location=Wallingford, UK |year=2008 |page=317 |isbn=978-0-85199-826-8}}
A hilum can also be a nucleus of a starch grain; the point around which layers of starch are deposited.
The adjectival form hilar denotes the presence of such a mark, and can be used as a distinguishing characteristic of a seed or spore.