follicle (fruit)

{{short description|Dry fruit which splits at a suture to release seeds from a single cavity}}

{{Use dmy dates|date=June 2023}}

Image:Milkweed-in-seed2.jpg follicle releasing its seeds.]]

In botany, a follicle is a dry unilocular fruit formed from one carpel, containing two or more seeds.{{cite book |author1=Hickey, M. |author2=King, C. |year=2001 |title=The Cambridge Illustrated Glossary of Botanical Terms |publisher=Cambridge University Press }} It is usually defined as dehiscing by a suture in order to release seeds,{{Cite EB1911|wstitle=Fruit|volume=11|page=257|first=Alfred Barton|last=Rendle|author-link=Alfred Barton Rendle}} for example in Consolida (some of the larkspurs), peony and milkweed (Asclepias).

Some difficult cases exist however, so that the term indehiscent follicle is sometimes used, for example with the genus Filipendula, which has indehiscent fruits that could be considered intermediate between a (dehiscent) follicle and an (indehiscent) achene.{{cite web|url=http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=112789|title=Flora of China online}}

An aggregate fruit that consists of follicles may be called a follicetum. Examples include hellebore, aconite, Delphinium, Aquilegia or the family Crassulaceae, where several follicles occur in a whorl on a shortened receptacle, or Magnolia, which has many follicles arranged in a spiral on an elongated receptacle.

The follicles of some species dehisce by the ventral suture (as in Banksia),{{cite journal|author1=Renshaw, A. |author2=Burgin, S. |year=2008|title=Enantiomorphy in Banksia (Proteaceae): flowers and fruits|journal=Australian Journal of Botany|volume=56|issue=4|pages=342–346|doi=10.1071/BT07073}} or by the dorsal suture (as in Magnolia).Kapil, R. N. and N. N. Bhandari (1964) [http://www.new1.dli.ernet.in/data1/upload/insa/INSA_1/20005b76_245.pdf Morphology and embryology of Magnolia] {{webarchive|url=https://web.archive.org/web/20130501164724/http://www.new1.dli.ernet.in/data1/upload/insa/INSA_1/20005b76_245.pdf |date=1 May 2013 }}. Proc. nat. Inst. Sci. India 30, 245–262.

File:Follicles of Helleborus foetidus.JPG|Follicles from Helleborus foetidus

File:Banksia integrifolia and marginata cones.jpg|Only some flowers in a Banksia inflorescence mature into follicles embedded in the "cone"

File:Stenocarpus sinuatus, vrugte, Manie van der Schijff BT.jpg|Follicles of Stenocarpus sinuatus will release papery brown seeds