The natural history of the genus Searsia (Anacardiaceae), part x: Fruit-form
Fruit-form:
No species of Searsia has fruit that remains succulent until separation from the plant by fruit-eaters, as seen in confamilials such as Sclerocarya caffra.
In the Rhus/Malosma/Searsia complex, the fruits vary, according to genus and species, in
- fleshiness,
- the adherence of endo- and mesocarp, and
- resinousness vs waxiness.
The least fleshy fruits occur in spp. common on the Cape Peninsula, in scrub intermediate between pyrophilic and pyrofugic, e.g.
- S. tomentosa (https://www.inaturalist.org/observations/204741450 and https://www.inaturalist.org/observations/199081589 and https://www.inaturalist.org/observations/244519387 and https://www.inaturalist.org/observations/244322850 and https://www.inaturalist.org/observations/193149460 and https://www.inaturalist.org/observations/192926300 and https://www.inaturalist.org/observations/141934972 and https://www.inaturalist.org/observations/141934972 and https://www.inaturalist.org/observations/109925399),
- S. incisa (https://www.inaturalist.org/observations/207938684 and https://www.inaturalist.org/observations/197447807 and https://www.inaturalist.org/observations/245283078 and https://www.inaturalist.org/observations/245050937 and https://www.inaturalist.org/observations/245393291 and https://www.inaturalist.org/observations/245283080 and https://www.inaturalist.org/observations/230158461 and https://www.inaturalist.org/observations/223611501 and https://www.inaturalist.org/observations/205205652 and https://www.inaturalist.org/observations/198766067 and https://www.inaturalist.org/observations/196920606), and
- S. angustifolia (https://www.inaturalist.org/observations/203205900 and https://www.inaturalist.org/observations/244461786 and https://www.inaturalist.org/observations/241702352 and https://www.inaturalist.org/observations/226868850 and https://www.inaturalist.org/observations/212290656 and https://www.inaturalist.org/observations/211008444 and https://www.inaturalist.org/observations/208569935 and https://www.inaturalist.org/observations/201104333 and https://www.inaturalist.org/observations/198718062 and https://www.inaturalist.org/observations/198568232 and https://www.inaturalist.org/observations/197344009 and https://www.inaturalist.org/observations/197289488 and https://www.inaturalist.org/observations/197167449),
Generally speaking, the spherical drupes of certain spp., e.g. Searsia dentata, Searsia crenata, Searsia chirindensis, and Searsia pyroides, are eaten by birds and monkeys while still fleshy. By contrast, the non-spherical, discoid fruits of e.g. Searsia undulata, Searsia burchellii, and Searsia lancea, are eaten by these animals also when 'post-ripe, i.e. when the exocarp of has dried without wrinkling (Rodney Moffett, who has taxonomically revised Rhus sensu lato, and is an author of https://www.researchgate.net/publication/322608644_A_review_of_the_ethnobotany_of_the_Basotho_of_Lesotho_and_the_Free_State_Province_of_South_Africa_South_Sotho, in email).
In Searsia incisa, the exocarp tends to crack. There is no suture as such, and some drupes simply crack spontaneously (owing to weathering or physical pressure) due to the fruit being relatively large, the stone small, and the exocarp thin. In this species one also finds some infructescences with the drupes so tightly packed that, when the individual fruits separate, it may give the impression of dehiscence.
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FRUIT-FORM IN SCHINUS MOLLE (Anacardiaceae)
Reference: Goldstein and Coleman (2004, https://www.researchgate.net/publication/304300366_Schinus_Molle_L_Anacardiaceae_Chicha_Production_in_the_Central_Andes and https://link.springer.com/article/10.1663/0013-0001(2004)058[0523:SMLACP]2.0.CO;2 and https://bioone.org/journals/economic-botany/volume-58/issue-4/0013-0001_2004_058_0523_SMLACP_2.0.CO_2/Schinus-Molle-L-Anacardiaceae-Chicha-Production-in-the-Central-Andes/10.1663/0013-0001(2004)058[0523:SMLACP]2.0.CO;2.short and https://www.proquest.com/docview/1112271461?sourcetype=Scholarly%20Journals)
The fruit is a drupe (https://en.wikipedia.org/wiki/Drupe).
For comparison, the following describes the drupe of the mango (Mangifera): https://www.researchgate.net/figure/Structure-of-mango-fruit-and-seed-kernel_fig2_362666400https://www.researchgate.net/figure/Structure-of-mango-fruit-and-seed-kernel_fig2_362666400).
An important point is that the seed of the mango consists of a fibrous, leathery, inedible endocarp, loosely encasing the actual kernel.
Goldstein and Coleman (2004):
"S. molle drupes are resin-encased woody seeds, wrapped in a bright red to purple papery exocarp"
The following defines 'exocarp': https://www.merriam-webster.com/dictionary/exocarp
Goldstein and Coleman (2004):
"The seeds of the S. molle fruits are known for volatile oils reminiscent of black pepper." The spicy substances remain even after the fruits (including the seeds) are deliberately fermented to make an alcoholic beverage (https://en.wikipedia.org/wiki/Chicha). The seeds, despite being subjected to bacterial action, retain their peppery taste, associated with essential oils (occurring also in the foliage of S. molle) that are useful for repelling insects.
Goldstein and Coleman (2004) describe the fruit thus:
"when mature, they have a papery exocarp that surrounds a seed with an invaginated outer wall inset with deep resin pockets. The fruits are 'ripe'...when the exocarp just begins to be papery, and the resin pockets are still slightly fleshy. At this stage, the resin pockets maintain a high level of concentrated sugars and are quite sweet...if the fruits become over-ripe and...dry, the sugary taste becomes bitter and the peppery flavor characteristic of the volatile oils of the seed transfer to the fruit. Similarly, under-ripe fruits will not have sufficiently developed resin pockets and will be quite bitter and juicy."
My commentary:
I suspect that the unripe fruit tastes astringent, not bitter. This is a common mistake in descriptions of the taste of plants.
Certain spp. of Searsia resemble confamilial S. molle in having 'hollow' fruit-pulp, in which the exocarp separates from what I assume to be the mesocarp (described above as 'resin pockets'). This separation means that the ripe fruits contain air instead of the fruit-pulp commonly consumed in the case of the mango.
However, there is a subtle aspect to this comparison. In the mango, the mesocarp is effectively two-layered, with the easily-eaten pulp plus an equally sweet, somewhat sour, and even tastier pulp permeating the fuzzy boundary of the fibrous endocarp. This is adaptive, in the sense that one tends, after eating most of the fruit-pulp of the mango, to suck/scrape at the seed, to extract the tasty jam-like material from the fibrous 'seed-wall'.
Despite some resemblance to Searsia, there are the following differences:
Firstly, as far as I know, no sp. of Searsia has ripe fruits that are as bright-hued (https://stock.adobe.com/images/bunch-of-bright-pink-color-fruits-of-schinus-molle-or-peruvian-pepper-on-the-tree-against-sunny-blue-sky-cuzco-region-peru/212241467) as those of S. molle, let alone when 'air-filled'.
However, see https://kumbulanursery.co.za/plants/searsia-incisa-var-effusa.
Secondly, as far as I know, no sp. of Searsia has peppery seeds.
What seems to be in common among mango, S. molle, and Searsia is that, in all cases, there is a tendency for the mesocarp (digestible to seed-dispersers) and the endocarp (indigestible because it protects the seed) to be intergraded to a degree that some delay results in the processing of the fruit and thus the discarding of the diaspore. This is adaptively significant, because the delay potentially boosts the distance of dispersal from the parent individual plant.
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