Opinions Sun, 29 Jun 2014

‘Atoaa’ is Ashanti plum (Spondias mombin)

Ashanti plum or hog plum or yellow mombin is the fruit that Asantes call ‘atoaa’. The Fantes call it ‘ataaba’, the Ewes ‘akukor’ and Ga people ‘aadon’. The Akan students at Cosmos Basic School, Lapaz, call it ‘akosia kokoo’. Botanically, it is called Spondias mombin. More correctly, the tree/plant is Spondias mombin but the fruit is the Ashanti plum. The word plum is a homophone of plumb, ie, both are pronounced as /plam/.

Spondias mombin is in the Anacardiaceae family, the botanical family that also contains cashew and neem. And in reality, the margins and colour of the leaves and shape of the fruit of Spondias mombin resemble those of neem tree (Azadirachta indica). Typical of most common names, Ashanti plum contains the word plum, but it is completely unrelated to the European tree called plums (Prunus spp.) which are in the Rosaceae family.

In addition to being in different botanical families, the Ashanti plum is a tropical species, but plum is a temperate species. Also, Ashanti plum is a wild plant (tree) whose fruits are only gathered and sold/eaten whereas plum is a crop grown commercially in Europe and in Asia. (The terms plant and crop are subtly different. A plant is any organism in the kingdom Plantae, but a crop is a plant that has been domesticated and cultivated for food or for raw materials, eg, cocoa, maize, rice and cotton. A plant grown to beautify the environment is called an ornamental plant.)

What the Ashanti plum and European plum have in common is that both species produce a unique type of drupaceous fruit informally termed ‘plums’. A ‘plum’ is smooth-skinned fruit that is nearly round or spherical and contains one seed which is usually large and occupies much of the space in the fruit. Other examples are West African blackplum (Vitex doniana), bloodplum (Haemostaphis barteri) and monkey plum (Ximenia spp.). All the other three ‘plums’ are indigenous to Ghana and each of them will be dealt in detail in a separate write-up. Like the Ashanti plum and the European plum, all these plums are botanically unrelated.

Only three of the features contained in the above definition are gallantly displayed by Ashanti plum, which is nearly oblong in shape. The most appropriate adjectives to describe the taste of Ashanti plum are limited to your tasting the fruit—a single bite and swallow will send the sharp tartly sour or sweetly bitter taste running from your tongue to the end of your jaws! (Photos of the seed, fruit and seedlings have been attached to this write-up. Those who want to see them may logon to @ http://www.spyghana.com/atoaa-ashanti-plum-spondias-mombin/. Or simply send a request via my phone number or email address below, for Ghanaweb rarely publishes photos).

Concerning dormancy, mode of germination and number of seedlings produced per seed, Ashanti plum has some interesting but somehow conflicting information. I noted that Ashanti plum seeds are recalcitrant, but other researchers especially Orwa et al (2009) reported that the seeds are orthodox. A recalcitrant seed is one that loses its viability once it dries, ie, it dies when it dries (eg, cocoa, rubber, avocado, cola, shea, mango and coconut). Recalcitrant seeds must be sown immediately they are extracted (removed from the fruit). Conversely, seeds which still germinate when they are dry are termed orthodox seeds (eg, maize, rice, okra, carica, tomato, eggplant, garden egg, cabbage and cowpea).

Ashanti plum seeds are dormant (remain in the moist soil for a longer period without germinating). I sowed 50 seeds on 13/07/2013; only 35 had germinated in March 2014 (see photo). The dormancy period is 8 to 10 months. This period of dormancy may be due to the woody nature of the seed (see photo). To hasten germination, you may scarify the seed using acids (eg, sulfuric acid). Alternatively, you may use sandpaper or file to rub the seedcoat to reduce its thickness prior to sowing.

The seeds of Ashanti plum germinate hypogeally (the cotyledons remain on or in the soil). Notice that defining hypogeal germination as ‘the type of germination in which the cotyledons remain in or below the soil’ is only applicable to farming where seeds are sown (buried in the soil). In nature, many seeds fall on the soil surface where they germinate. Here, the cotyledons of hypogeally germinating seeds remain on the soil surface (this situation is common for large seeds such as avocado).

In consequence, hypogeal germination is better defined as ‘the germination in which the cotyledons remain on or below the soil level’. That is, the epicotyl (part of the germinating seed or seedling immediately above the cotyledons) elongates to push the plumule (young shoot) above the soil level. Consequently, the hypocotyl (part of the seedling below the cotyledons) idles—does not elongate to push the cotyledons upwards. Contrastingly, epigeal germination is the type in which the cotyledons are lifted above the soil level (regardless of whether the seed was buried or it was on the soil surface).

Thus, the distinction between hypogeal and epigeal germination depends on which part of the germinating seed elongates to push the plumule above the soil. In hypogeously germinating seeds, the epicotyl elongates, but in epigeously germinating seeds, the hypocotyl elongates. Being below the cotyledons, the elongating hypocotyl automatically pushes the cotyledons above the soil level making the germination epigeal.

Often, the mode of germination in most seeds can be determined by considering cotyledon morphology (number and size). All monocotyledonous seeds such as maize, coconut, bamboo and yam germinate hypogeally. Interestingly, dicotyledonous seeds or dicots exhibit both hypogeal and epigeal germination. In general, large-seeded dicots exhibit hypogeal germination because their hypocotyls are too thin and weak to lift the massive cotyledons from or above the soil level. Hence, dicots such as avocado, mango and shea germinate hypogeally. Here, many integrated /in-ti-grei-ted/ science ‘textbooks’ (eg, Aki–Ola Integrated Science for SHS) wrongly list mango as exhibiting epigeal germination. Only common sense refutes this miserably.

Seed size is not a good predictor of germination pattern, however. Some relatively small-seeded dicots germinating hypogeally are Bambara groundnut (Vigna subterranea), African locust bean (Parkia biglobosa) and pea (Pisum sativum). In the botanical name for Bambara groundnut, the species name ‘subterranea’ is the source of the English adjective ‘subterranean’—meaning underground. It tells us that Bambara groundnut produces it fruits (pods) in the soil. The genus name Vigna is derived from the surname of Prof Dominico Vigna, the 17th century Italian botanist.

To the number of seedlings produced per seed, I observed that out of my 35 germinated yellow mombin seeds, 24 of them produced 2 seedlings each. The phenomenon whereby a single seed produces two or more seedlings is termed polyembryony. Thus, Spondias mombin produces polyembryonic seeds. Other examples of plants that produce polyembryonic seeds are sweet orange (Citrus sinensis), mango (Mangifera indica) and ackee (Blighia sapida).

Never hesitate to drop a comment, for I’m on guard to respond if necessary. Long live practising teachers! Long live Kwame Nkrumah’s Ghana!

Idris Pacas: 020 910 153 3 & iddrisuabdulai12@yahoo.com
Columnist: Pacas, Idris