The genus Casimiroa of the family Rutaceae was named in honor of Cardinal Casimiro Gomez de Ortega, a Spanish botanist of the 18th Century*. It embraces 5 or 6 species of shrubs or trees. Of these, 3 shrubby species, C. pubescens Ramirez, C. pringlei Engl. and C. watsonii Engl., are apparently confined to Mexico and have received scant attention. An additional species, C. emarginata Standl. & Steyerm., was described in 1944, based on a single specimen in Guatemala. It may be merely a form of C. sapota, below.
[*The genus Casimiroa was actually named after Casimiro Gomez, an Otome Indian from the town of Cardonal, Hidalgo, Mexico, a martyr of Mexico's war of independence.]
Of the 3 larger-growing forms, the best known is the common white sapote, called zapote blanco by Spanish-speaking people, abché or ahache by Guatemalan Indians, and Mexican apple in South Africa, and widely identified as C. edulis Llave & Lex. The matasano (or matazano), C. sapota Oerst., is often not distinguished from C. edulis in the literature and the name matasano has been applied to other species in various localities. The woolly-leaved white sapote, known to the Maya as yuy and set apart in Guatemala as matasano de mico, has been commonly considered a distinct species, C. tetrameria Millsp., but it may be only a variant of C. edulis.
Fig. 48: A seedless white sapote, natural size, photographed by Dr. David Fairchild at Orange, California, in October 1919. In his notes accompanying the picture in Inventory of Seeds and Plants Imported, No. 60, he says: "It is not rare for trees of this species...may often be due to defective pollination." (Bureau of Plant Industry, United States Department of Agriculture)
White sapote trees range from 15 to 20 ft (4.5-6 m) up to 30 to 60 ft (9-18 m) in height. They have light-gray, thick, warty bark and often develop long, drooping branches. The leaves, mostly evergreen are alternate, palmately compound, with 3 to 7 lanceolate leaflets, smooth or hairy on the underside. The odorless flowers, small and greenish-yellow, are 4- or 5-parted, and borne in terminal and axillary panicles. They are hermaphrodite or occasionally unisexual because of aborted stigmas.
The fruit is round, oval or ovoid, symmetrical or irregular, more or less distinctly 5-lobed; 2 1/2 to 4 1/2 in (6.25-11.25 cm) wide and up to 4 3/4 in (12 cm) in length; with thin green, yellowish or golden skin coated with a very thin bloom, tender but inedible; and creamy-white or yellow flesh glinting with many tiny, conspicuous, yellow oil glands. The flavor is sweet with a hint or more of bitterness and sometimes distinctly resinous. There may be 1 to 6 plump, oval, hard, white seeds, 1 to 2 in (2.5-5 cm) long and 1/2 to 1 in (1.25-2.5 cm) thick, but often some seeds are under-developed (aborted) and very thin. The kernels are bitter and narcotic.
C. edulis has leaves that are usually composed of 5 leaflets, glabrous to slightly pubescent on the underside, and 5-parted flowers. The fruit is somewhat apple-like externally, generally smooth, fairly symmetrical and 2 1/2 to 3 in (6.25-7.5 cm) wide. C. sapota is very similar but the leaves usually have only 3, somewhat smaller, leaflets. The woolly-leaved white sapote usually has 5 leaflets, larger and thicker than those of C. edulis and velvety-white on the underside, and all the parts of the flowers are in 4's. The fruits are usually 4 to 4 1/2 in (10-11.25 cm) wide, ovoid, irregular and knobby, with rough, pitted skin, and there are often gritty particles in the flesh.
Origin and Distribution
The common white sapote occurs both wild and cultivated in central Mexico. It is planted frequently in Guatemala, El Salvador and Costa Rica and is occasionally grown in northern South America, the Bahamas, West Indies, along the Riviera and other parts of the Mediterranean region, India and the East Indies. It is grown commercially in the Gisborne district of New Zealand and to some extent in South Africa. Horticulturists in Israel took serious interest in white sapotes around 1935 and planted a number of varieties. The trees grew well and produced little in the coastal plain; bore good crops in the interior and commercial prospects seemed bright but the fruit did not appeal to consumers and was too attractive to fruit flies. White sapotes have not done well in the Philippines. The common species was introduced into California by Franciscan monks about 1810, and it is still cultivated on a limited scale in the southern part of that state. In Florida, it was first planted with enthusiasm. Today it is seldom seen outside of fruit tree collections. Of course, many of the trees planted have been seedlings bearing fruits of inferior size and quality, but even the best have never attained popularity in this country.
C. sapota is wild in southern Mexico and Nicaragua, commonly cultivated in Oaxaca and Chiapas. The woolly-leaved white sapote is native from Yucatan to Costa Rica and has not been widely distributed in cultivation. According to Chandler, the fruits are objectionably bitter in California. In southern Florida, the woolly-leaved is sometimes planted in preference to C. edulis.
White sapote trees often are grown strictly as ornamentals in California. They are planted as shade for coffee plantations in Central America.
Clonal selections were made in California from about 1924 to 1954, and several also in Florida. Some of these may actually be chance hybrids. A surprising number have been named and propagated: 'Blumenthal', 'Chapman', 'Coleman', 'Dade', 'Flournoy', 'Galloway', 'Gillespie', 'Golden' or 'Max Golden', 'Johnston's Golden', 'Harvey', 'Lenz', 'Lomita', 'Maechtlen', 'Maltby' or 'Nancy Maltby', 'Nies', 'Page', 'Parroquia', 'Pike', 'Sarah Jones', 'Suebelle', or 'Hubbell', 'Walton', 'Whatley', 'Wilson', 'Wood', 'Yellow'.
'Coleman'was one of the first named in California; fruit is oblate, somewhat lobed, furrowed at apex; to 3 in (7.5 cm) wide; skin is yellow-green; flesh of good flavor (22% sugar) but resinous; seeds small. Fruit ripens from late fall to summer. Tree somewhat dwarf; leaflets small and tend to twist. Difficult to propagate.
'Dade'grown at the Agricultural Research and Education Center, Homestead, Florida from a seed of a selected fruit of a local seedling tree. It was planted in 1935 and fruited in 1939. Round; skin golden-yellow tinged with green, thin; flesh of good, non-bitter flavor. There are 4 to 5 seeds. Ripens in June-July. The tree is low-growing and spreading, with smooth leaflets.
'Gillespie'originated in California; fruit is round, 3 in (7.5 cm) wide; skin is light-green with russet cheek, fairly tough, rough; flesh is white, of very good flavor. Tree is prolific bearer.
'Golden', or 'Max Golden'woolly-leaved; fruit conical, depressed at apex; up to 4 1/2 in (11.25 cm) wide; skin yellow-green, fairly tough; flesh has strong flavor, somewhat bitter; few seeds.
'Harvey'originated in California; round; 3 1/2 in (9 cm) wide; skin smooth, yellow-green with bright orange cheek; flesh cream-colored to pale-yellow; not of the best flavor. Tree is a prolific bearer.
'Maechtlen'named for the parent, an old tree on property owned by the Maechtlen family in Covina, California. Propagated by budding and sold by nurserymen in the 1940's.
'Maltby', or 'Nancy Maltby'originated in California; round, faintly furrowed, blunt-pointed at apex, base slightly tapered; large; skin yellow-green, smooth, of good flavor but slightly bitter. Tree bears well.
'Parroquia'originated in California; oval, 2 1/2 in (6.25 cm) wide, 3 in (7.5 cm) long; skin yellow-green, smooth, thin; flesh ivory, of very good flavor. A fairly prolific bearer.
'Pike'originated in California; rounded or oblate, slightly 5-lobed; to 4 in (10 cm) wide; skin green, very fragile; flesh white to yellowish, of rich, non-bitter, flavor. The tree bears regularly and heavily in California and South Africa.
'Suebelle', or 'Hubbell'originated in California; round; medium to small; skin green or yellowish-green; of excellent flavor (22% sugar). Tree is precocious and blooms and fruits all year. Fairly widely planted in California.
'Wilson'originated in California; round to oblate; medium to large; skin smooth, medium thick; flesh of high quality and excellent flavor. Fruit ripens in fall and winter or more or less all year. Tree bears heavily and has been rather widely planted in California.
'Yellow'originated in California; oval with pointed apex, furrowed; skin is bright-yellow and fairly tough; flesh is firm. Fruit keeps well. Tree bears regularly and heavily in California.
There is a great variation in the amount of pollen produced by seedlings and grafted cultivars. Some flowers bear no pollen grains; others have an abundance. Sterile pollen or lack of cross-pollination are suggested causes of aborted seeds and heavy shedding of immature fruits. In Florida, flowers of some heavy-bearing, double-cropping, trees have been observed so heavily worked by bees that their humming is heard several feet away.
The white sapotes can be classed as subtropical rather than tropical. C. edulis is usually found growing naturally at elevations between 2,000 and 3,000 ft (600-900 m) and occasionally in Guatemala up to a maximum of 9,000 ft (2,700 m) in areas not subject to heavy rainfall.
In California, light frosts cause some leaf shedding but otherwise do not harm the tree. Mature trees have withstood temperature drops to 20º F (-6.67º C) in California and 26º F (-3.33º C) in Florida without injury.
The trees prosper near the coast of southern California where the mean temperature from April to October is about 65º F (18º C). They do poorly and often fail to survive further north near San Francisco where the mean temperature for the same period is 57º to 58º F (13.89º-14.44º C). The woolly-leaved is somewhat less hardy than the common white sapote.
As long as there is good drainage, the trees will do very well on sandy loam or even on clay. In California, some of the early plantings were on light, decomposed granite soil, and they were fruitful for many years. In Florida, the trees grow and fruit well on deep sand and on oolitic limestone, though, on the latter, they may become chlorotic. They are fairly drought-resistant.
White sapotes are commonly grown from seeds and seedlings usually begin to bear in 7 or 8 years. Grafting is a common practice in California and Florida in midsummer. Seedlings of 'Pike', being vigorous growers, are preferred as rootstock. Shield-budding and side-grafting in spring onto stocks up to 3/4 in (2 cm) thick give good results. Cleft grafts and slot grafts are made on larger rootstocks and when topworking mature trees. Grafted trees will start bearing in 3 or 4 years. Commercial growers in New Zealand have had success with air-layers. Cuttings are very difficult to root.
In California, the young trees are cut back to 3 ft (0.9 m) when planted out, in order to encourage low-branching. As the branches elongate, some pruning is done to induce lateral growth.
Fertilizer formulas should vary with the nature of the soil, but, in general, the grower is advised to follow procedures suitable for citrus trees. Many white sapote trees have received little or no care and yet have been long-lived. One of the original trees in Santa Barbara, California, was said to be over 100 years old in 1915.
In the Bahamas, the fruits ripen from late May through August. In Mexico, flowering occurs in January and February and the fruits mature from June to October. In Florida there is usually just a spring-summer crop, but a heavy-bearing woolly-leaved tree in Miami blooms in December, fruits in the spring, blooms again and produces a second crop in the fall. In California, 'Pike' and 'Yellow' bloom in the spring and again in late summer and fall, the fruits from late blooms maturing gradually over the winter. 'Suebelle' blooms for 6 to 8 weeks in spring and again in midsummer and fruits ripen in September and October.
Mature fruits must be clipped from the branches leaving a short piece of stem attached. This stub will fall off naturally when the fruits become eating-ripe. If plucked by hand, the fruits will separate from the stem if given a slight twist but they will soon show a soft bruised spot at the stem-end which quickly spreads over much of the fruit, becoming watery and decayed. The fruits must be handled with care even when unripe as they bruise so easily and any bruised skin will blacken and the flesh beneath turns bitter. If picked just a few days before fully ripe and ready to fall, the fruits turn soft quickly but they can be picked several weeks in advance of the failing stage and most will develop full flavor. 'Pike', however, if picked a month early, will take 2 weeks to ripen and will be substandard in flavor. Fruits that have ripened on hand will keep in good condition in the home refrigerator for at least 2 weeks. Fruits from commercial orchards are graded for size, wrapped individually to retard full ripening, packed in wooden boxes, and well-padded for transportation under refrigeration.
Pests and Diseases
The white sapote has few natural enemies but the fruits of some cultivars are attacked by fruit flies. Black scale often occurs on nursery stock and occasionally on mature trees in California.
Fig. 49: The common white sapote (Casimiroa edulis) (left) and the woolly-leaved white sapote, often called C. tetrameria (right). The latter may be only a variant of C. edulis.
Within its native range, the white sapote is commonly eaten out-of-hand. The flesh of ripe fruits may be added to fruit cups and salads or served alone as dessert, but it is best cut into sections and served with cream and sugar. Sometimes it is added to ice cream mix or milk shakes, or made into marmalade. Even in their countries of origin, where the fruits may at times appear in markets, their repute is due largely to a belief in their therapeutic value, while, at the same time, there prevails a fear that over-indulgence may be harmful. The epithet "matasano" (interpreted as "kill health") has a sinister connotation. Dr. J.B. Londoño, in his Frutas de Antioquia, published in Medellin, Colombia, in 1934, referred to the white sapote as disagreeable and indigestible. Some years ago in Central America there were unsuccessful efforts to manufacture from the pulp an acceptable preserve. In processing trials at the Western Regional Research Laboratory of the United States Department of Agriculture, Albany, California, technologists decided that white sapotes; are not suitable for either canning in sirup or freezing as a puree.
|Food Value Per 100 g of Fresh Pulp*|
|Ascorbic Acid||30.3 mg|
*According to analyses made in El Salvador.
As bearers of edible fruits, the white sapotes, despite their prolificacy, will doubtless continue to occupy the minor position which they now hold in subtropical horticulture.
The seed is said to be fatally toxic if eaten raw by humans or animals.
Seeds: In 1959, Dr. Everette Burdick, Consulting Chemist, of Coral Gables, Florida, made several extractions from the kernels, securing small amounts of needle-like yellow crystals. From one process, a yellow resinous mass resulted which functioned as an attractive and lethal bait for American cockroaches, having the advantage of killing on the spot rather than at some distance after ingestion of the poison. The United States Department of Agriculture's Agricultural Handbook 154, Insecticides from Plants, mentions no experiments with Casimiroa seed extracts but reports that extracts from branches and leaves of C. edulis are non-toxic to both American and German roaches.
Wood: The wood is yellow, fine-grained, compact, moderately dense and heavy, medium strong and resistant, but not durable for long. It is occasionally employed in carpentry and for domestic furniture in Central America.
Medicinal Uses: The ancient Nahuatl name for the fruits, "cochiztzapotl", is translated "sleepy sapote" or "sleep-producing sapote", and it is widely claimed in Mexico and Central America that consumption of the fruit relieves the pains of arthritis and rheumatism. This belief may stem only from the oft-quoted statement to this effect by Dr. Leopoldo Flores in Manual Terapeutica de Plantas Mexicanas, published in 1907, although the Mexican National Commission has received frequent reports of anti-arthritic, anti-rheumatic effects from physicians and their patients.
The eminent Francisco Hernandez, in his writings during the period 1570-1575 (translated and published as Rerum Medicarum Novae Hispaniae in 1651), noted that eating the fruit produced drowsiness. He referred to the seeds as "deadly poison" but efficacious, when crushed and roasted, in healing putrid sores. This vulnerary use of the seeds is cited in the obsolete Farmacopea Mexicana, where the fruit is mentioned as a vermifuge. For many years, extracts from the leaves, bark, and especially the seeds have been employed in Mexico as sedatives, soporifics and tranquilizers.
The narcotic property of the seeds was first identified as an alkaloid by Dr. Jesus Sanchez of Mexico in his thesis, Breve estudio sobre la almendra del zapote blanco, in 1893; and, in 1898, it was made the subject of chemical study by an especially appointed commission. One of the investigators, Alfonso Altimirano, reported the isolation of a glucoside as a pale yellow, amorphous mass, at first sweet but with a prolonged bitter aftertaste. White sapote derivatives were among the medicinal plant products displayed at the St. Louis Exposition in 1904 and explained in the slender book, Materia Medica Mexicana: A Manual of Mexican Medicinal Herbs, prepared by the Mexican National Commission for that occasion.
In 1900, a quantity of white sapote seeds was sent from Mexico to F.H. Worlee & Co., in Hamburg, Germany, with an accompanying explanation that both the fruit and the seeds possessed sleep-inducing principles but without the undesirable after-effects of opium. This material came to the attention of W. Bickern. He proceeded to work on the seeds, from which he obtained a substance which he called an alkaloidal glycoside, casimirin. In France, several investigators confirmed the narcotic nature of the seeds. Subsequently, Frederick Power and Thomas Callan of the Wellcome Chemical Research Laboratories in London, declared that, though they isolated 6 substances including 2 alkaloids, casimiroine and casimiroedine, there was "no evidence of the presence of a definite glucoside or a so-called glucoalkaloid ...and physiological tests conducted with animals ...likewise failed to confirm . . . reported hypnotic or toxic properties." Meanwhile, the seed extracts, in liquid, capsule, or tablet form, continued in use in Mexico, one product bearing the trade name "Rutelina".
In 1934, José de Lille proceeded to test the effect on blood pressure of dogs. He found a dose of .20 g per kilo of animal weight to be definitely hypotensive. A large dose (1 g) administered to a dog weighing 11 lbs (5 kg) produced a drastic lowering of blood pressure which persisted even after a brief rise induced by injecting adrenalin. In 1936, M. Mendez described the preparation of a tincture of "a clear yellow color with neither special odor nor taste" which produces "a state of depression in the entire nervous system, especially in the sensory sphere, and sleep." Dr. Faustino Miranda reported that an infusion of the leaves of Casimiroa sapota is used for similar purposes, and he assumed that this species has the same properties as C. edulis. According to Materia Medica Mexicana, the extracts from the leaves and bark are half as strong as those from the seeds and can be safely administered to children. In Costa Rica, the leaf decoction is taken as a treatment for diabetes.
In 1956, four chemists, F. Kinel, J. Rosso, O. Rosenkranz and F. Sondheimer, on the staff of the Mexican branch of the pharmaceutical company, Syntex, undertook chemical studies of the seeds. They did not find the "gluco-alkaloid" casimirin, but isolated 13 substances, 6 of which coincided with those reported by Power and Callan. One of these, casimirolid, was later found by F. Sondheimer, A Meisels and F. Kinel, to be identical with obacunone, an attribute of citrus oil. Of the 7 additional compounds, one palmitamide, had not previously been noted in the plant kingdom. Another, N-benzoyltyramine, they suggested might have much to do with the reputed potency of the seed, for tyramine is one of the active principles of ergot (is also found in mistletoe and thistle) and is well known for its physiological action. The main alkaloid of the seeds, casimiroedine, representing 0.143%, was crystallized in the form of needles.
Investigations of the bark from the trunk and roots of C. edulis were undertaken for Syntex by J. Iriarte, F. Kinel, O. Rosenkranz and F. Sondheimer. No casimiroedine was found but 12 substances were identified, only 2 of which, zapotin and casimiroin, occur in the seeds. The root bark contained .22% of the latter, while the seeds yielded only 0.0076%. In 1957, Meisels and Sondheimer announced that one of the bark alkaloids, edulein, which they had considered new, is identical with an alkaloid found in the bark and leaves of Lunaria amara Blanco, a citrus relative of Malayan origin. In 1958, R.T. Major and F. Dürsch, of the Cobb Chemical Laboratory, University of Virginia, working under a grant from Merck & Co., isolated from C. edulis seeds a compound which they identified as Na, Na-dimethy1histamine, formerly found in nature only in the sponge, Geodia gigas. J.S.L. Ling, S.Y. P'an and F.A. Hockstein, of Chas. Pfizer & Co. Research Laboratories, Brooklyn, New York, in experimental work with this compound in rabbits, dogs and cats, observed strong vasodepressive action. Dr. Hockstein suggested that all of the hypotensive properties and at least part of the sedative and pain-relieving qualities could be attributed to this compound, which "is not considered acceptable in man".
In early July of 1960, the writer furnished approximately 2 bushels of largely overripe, fallen fruits of C. edulis and the woolly-leaved white sapote to Delta Pharmaceuticals of Hialeah, Florida. They readily extracted from the seeds a soporific substance, 50 mg of which, taken by humans, induced sound sleep within 2 hours, with no apparent ill effects. The extract also acted as a narcotic on goldfish.
The following statement (translated from Spanish) is made in a communication received in 1961 from the Sección Administrativa, Dirección de Control de Medicamentos, Secretaria de Salubridad y Asistencia, Mexico City: "In Mexico, the white sapote is not used other than in folk medicine and not in any way by pharmacists nor doctors; neither is it an official drug in the Pharmacopoeia".
In India, extensive studies have been made of the seeds, roots and bark, which contain histamine derivatives with strong hypotensive activity, as well as furoquinoline alkaloids and 2-quinolones and 4-quinolones, including edulein, edulitin, edulinine and casimiroin. Also present are coumarins, flavonoids, and limonoids, including zapoterin, zapotin, zapotinin, casimirolid, deacetylnomilin, and 7-a-obacunol. Leaves and twigs yield isoplimpinellin (diuretic) and n-hentriacontane (anti-inflammatory).