This article is about fruitstones. For the organelle within the chloroplast of some algae and hornworts, see
pyrenoid. For other uses of "pyrene", see
Pyrene (disambiguation).
A pyrena or pyrene (commonly called a "pit" or "stone") is the fruitstone within a
drupe or
drupelet produced by the
ossification of the endocarp or lining of the fruit.[1] It consists of a hard
endocarp tissue surrounding one or more
seeds (also called the "kernel").[2][3] The hardened endocarp which constitutes the pyrene provides a protective physical barrier around the seed, shielding it from
pathogens and
herbivory.[4]
While many drupes are monopyrenous, containing only one pyrene,
pome-type fruit with a hard, stony (rather than leathery)
endocarp are typically polypyrenous drupes, containing multiple pyrenes.[5]
Cross-section of a
peach, a monopyrenous drupe, cut to reveal the pyrene inside
Pyrene of a
peach dissected to reveal a single seed inside
Pyrenes extracted from a single fruit of Crataegus punctata, a polypyrenous drupe
X-ray of a pyrene of Elaeocarpus ganitrus revealing 10 seed-bearing
locules inside; the number of locules in E. ganitrus pyrenes is variable between individual fruits