"Portulacaria afra, the Elephant's Food or Spekboom:

a monograph which contains some of the areas of

both knowledge and ignorance pertaining to this plant"

by Robert J. Baran

© 1999-2001


 

TABLE OF CONTENTS
PART I
TAXONOMY
ORIGIN
HISTORICAL REFERENCES
APPEARANCE
THE TRUNK
THE BRANCHES
THE LEAVES
THE FLOWERS AND FRUIT
THE ROOTS
VARIETIES
 
PART II
TEMPERAMENT
PROPAGATION
HORTICULTURAL & OTHER USES
CONTAINERIZED
BIBLIOGRAPHY
 
PART III
 THE OTHER PORTULACARIA
THE FALSE PORTULACARIA
BIBLIOGRAPHY


PART II



TEMPERAMENT

Outdoors, Sunset Zones 13, 16, 17, 22-24.  Outdoors with overhead protection, Sunset Zones 8, 9, 12-15, 18-21.  As a houseplant, anywhere with adequate bright light.  Will not stand much frost, and should be grown as a succulent, although P. afra seems to thrive in a wider range of soil conditions.  In the wilds of South Africa, large plants do survive the cutting frosts of bitter winters by growing dense enough to provide their own natural cover.  Drought tolerant and fire resistant, it will endure desert sun and heat which the jade plant will not.  Water well, and then let the soil dry out completely.  Chronic overwatering can kill the plant by easily encouraging the growth of fungus.  Soft or soggy branches are a sign of too much water.  This plant does not do well in continually humid locations.  Leaves turning black and falling, stem ends turning black and going soft, roots rotting, these are signs of the plant being too cold and probably too wet.  Pare off the blackened parts of the stem and dust with hormone rooting powder containing fungicide.  Keep in a location with temperatures above 40F (4C).

In the wilds a mistletoe, Viscum crassulae, is known to be a parasite of P. afra.

Resistant to diseases, sometimes the leaves can get aphid or white fly parasites in relatively small quantities with no harm to the plant.  Spider webs at the branch tips can be unsightly but effective in controlling the aforementioned insects.  Ants might also control the insects. 

The nematode Meloidogyne incognita is listed as a pathogen to many plants in Hawaii, including P. afra.

Mealy bugs and root mealy bugs have also been mentioned as likely problems.  For the former, remove the insects with a small paintbrush dipped in methylated spirits, and spray with a contact or systemic insecticide.  Repeat every 2 weeks until clear.  For the latter, likely if bottom leaves fall and there is little new growth, wash all soil off the roots, swirl in a contact insecticide, and allow to dry before repotting in fresh compost and a washed pot.  Leave dry for two weeks, giving not more than an hour or so of direct sun during this time.

Minor injuries to leaves heal with brownish-white scars.  Ants or leaf-cutting bees, for instance, might be responsible for partial damage on a small number of larger leaves on landscape plants.  The damaged edges seal and the leaf -- and plant -- goes on with its normal life. 

Vine weevils may be responsible when round pieces are missing from leaf edges and the stem is swollen and there is little new growth.  In this case, either use a systemic insecticide to kill the larvae in the stem, or prune the stem from the base and remove slices of the stem until the larvae are found.  Dispose of the larvae and reroot the remaining stem.

P. afra will not tolerate some chemical sprays, particularly petroleum-based chemicals.  Defoliation, followed by quick recovery, has been noted after exposure to Isotox and Malathion.  However, Volck Oil Spray appears to have no affect.  Soapy water or just the pressure from a garden hose seems to be sufficient in ridding the plant of most insect pests.

There have been limited observations of birds picking at leaf pads and branch tips, causing minor damage thereto.  House cats and dogs are generally indifferent to P. afra, although the latter have infrequently been known to chew on/tear up smaller specimens as part of a reaction to any non-grass vegetation within their territories.  This may be due to canine boredom. 

Small (.5 to 2 mm) roundish slightly raised or flat "pimples" of brown or green sometimes are seen on a very small quantity of the leaves.  (A single one-gallon container nursery specimen has been seen, however, which had approximately one sixth of its leaves bearing these marks without other noticeable difference.)  Usually only one mark is observed on a given leaf, though up to four (of "mixed heritage") have been recorded.  They seem to occur slightly more frequently on the upper surface of the leaf than on its lower surface, although they have been observed on both sides of the same leaf.  (In that case, the marks were on different places on their respective surfaces -- no apparent correspondence existed between the "pimples.")  It is extremely rare to discover adjacent leaves that both have such marks.  New leaves have never been observed to have "pimples" of any types.  While the pattern of surface pores has been observed to remain intact across the leaf and the blemishes, the "pimples" have been found to exit just on the thin top skin layer, not visibly extending into the leaf pulp.  Their etiology is unknown, and there probably is more than one cause for these features.  They seem to pose no long-term threat to the leaves having them, and they may last for the entire "adult" life of the affected leaf.

It is not clear what the symptoms are of specific nutritional deficiencies in P. afra.

 To Table of Contents
..


PROPAGATION

Cuttings root very easily in most potting media without either rooting hormone or "greenhousing" with an enveloping plastic bag or glass jar, for example, if the cut end is given at least a little moisture.  It should never be kept wet.  The minimum survivable cutting size appears to be about 5 cm in length and at least 3 mm in diameter.  At least double that length seems optimal.  Semi-ripe cuttings taken in summer are most recommended, but fresh cuttings taken from outdoor plants as late as mid-December in Sunset Zone 13 and then raised indoors without special care are also successful.  It is said that cuttings over 2.5 cm in diameter need to have a dry callous form over the end which is to be rooted before this can occur.  Limited experience shows that Sunset Zone 13 cuttings of that diameter taken in June did not need to be dried to give good results. 

Removing a number of the smaller branches and cutting the remaining leaves in half appears to aid in preventing moisture loss on newly struck cuttings.  New growth can be expected to be seen within a week during warm weather, arising initially at the base of removed branches.  Allowing essentially all secondary growth and leaves to remain on a cutting could result in dehydration and withering of branch tips and older leaves, and delay the rise of new leaves.  It is not known how large and branched a non-defoliated cutting can be before it does not still successfully root.  Defoliation can be done up to several weeks after the cutting is struck: it appears that the sooner it is done, the quicker the cutting will root and leaf.  It is thus very easy to quickly get a well-shaped tree from a trimmed branch. 

Unburied discarded prunings of sufficient size have been known to root by themselves on either poor or good soil in a south-facing exposure in the springtime in Phoenix if an adequate (but as yet undetermined small) amount of moisture is gotten within a few days. 

Cuttings can form good rootage of varied width and whose upper portion is sufficiently gnarly within three or four years. 

The recommendation to allow cuttings to "harden off" a couple of days before inserting in fast draining, dry soil mix comes from Portulacaria expert James J. Smith, Vero Beach, Florida (Sunset Zone 26).  It is possible that that more humid location (on the eastern coast between Cape Canaveral and West Palm Beach) might have slightly different requirements than those needed to successfully strike cuttings in the arid desert area of Phoenix (Sunset Zone 13). 

Elsewhere it is recommended to strike the cuttings in spring and summer, dust with hormone rooting powder, leave to dry for a few days, then root in dry compost.  Water after about 3 weeks when roots start to appear.  [The use of rooting hormone with this plant seems of more benefit to the gardener's peace of mind than to an actually improved success with cuttings. --RJB]

If green branched cuttings are rooted, the lignification browning will be much delayed.  There is some evidence that cool weather can cause this browning to happen or at least speed up its occurrence. 

Suckers occasionally arise at or below the soil level from nodes. Leaves and stalks which start below the soil level are pale green before emerging. 

Also possible to propagate from seeds, if obtainable, but these are rarely available.  The tiny seedlings should not be allowed to dry out for the first 6 months.  It is recommended to grow the seeds in a half pot or tray which stands in an outer container of water until the seed tray surface is damp.  Use of seeds is of questionable necessity given the readiness of cuttings to root. 

It is not known if larger mature pads can propagate in the manner of some true succulents, i.e. by being placed on top of dry sand or having their bases covered with potting medium.  Preliminary tests in Phoenix, Arizona indicate to the contrary, although positive anecdotal evidence comes from Vero Beach, Florida.  It is not known whether or not trailing joints in contact with soil will produce roots.  Observations have not yet disclosed any evidence of this either, although one anecdote to the positive has been heard..  It is not known how long untreated cuttings can remain viable.  It is not known how long rooted cuttings or specimens can remain viable without water or soil.  It is not known how well cuttings root in only water.  It is not known how much, if any, the lunar phases might affect propagation success or overall growth rates.

 To Table of Contents
..


HORTICULTURAL & OTHER USES

Where hardy, can be used as a fast-growing informal screen, unclipped hedge or cut back as a high-growing ground cover.  By the late 1950s in the U.S., P. afra was little-known but grown in California for interest more than ornament, and also in cool greenhouses northward.

Available at nurseries in one to five gallon pots.  Rooted cuttings of "Variegata" have been offered in 2" and 4" and 6" liner pots.  (The species name has been seen on some factory-printed plastic identification strips as "afro.")  Cactus and succulent clubs also have offered rooted cuttings for sale.  It is said that the plant is so common in South Africa that some nurseries don't bother to stock it.

Some 50 km north and west of the aforementioned Addo is the Rockcliff Game Farm.  The Spekboom, a favorite of the kudu -- Tragelaphas strepsiceros, the Eastern Cape kudu -- occurs widely there. This nutritious plant can support a higher biomass of large animals than any other ecosystem in South Africa.

It is reported to serve as a source of ostrich feed on farms in the Cape Province.

     "In some areas it is exploited by browsers such as goats, as most Spekboom is extremely palatable.  A sour form identical to the sweet form is, however, never or rarely browsed by domestic or wild ungulates.
     "[It forms] the backbone of the goat industry."  (Bredenkamp et al)

     "Spekboom is browsed by all kinds of stock, cattle and goats in particular being very fond of it.  Cattle and large buck, such as kudu, have done great damage in spekboom country by tearing down branches, which are very brittle.  Spekboom was a favourite food of the elephant which once roamed parts of the Eastern province.  In difficult years it has been a great stand-by to farmers as it is extremely drought resistant, nourishing, and has a high moisture content.  Farmers claim that there are two varieties of the plant, the sweet and the sour, and that stock show a marked preference for the former.  Botanists, however, find no structural difference between the so-called 'sweet' and 'sour.'
     [Plants that grow on grow on an eastern or northern aspect are sweet and very well grazed, while those on southerly or westerly aspects, or on shale are sour and not well grazed.  The latter contains much tannin.]
     "In parts, spekboom is eaten by people as well as animals.  Zulus eat the leaves raw.  In Portuguese East Africa, African [Khoisan] women are said to eat them when they are short of milk to feed their babies, as they increase the milk supply.  In the northern Transvaal Africans use the dry ground leaves in snuff.
     "In the dry Fish River Valley in the eastern Cape where there is no grass suitable for thatching, Africans sometimes use instead the stems and branches of the spekboom.  The dried stems are beaten with stones until flat and are then packed on top of each other to form a rather untidy but efficient thatch.  This is leading to the destruction of great numbers of spekboom in the valley.
     "Spekboom, which grows densely in its natural state as a tree, or as a bush often draping a hillside, is valuable for its soil-binding properties [and is planted in certain areas to assist in veld reclamation].  It also makes a neat clipped hedge for gardeners."  (Palmer, pg. 568)

By 1899 it had been exported to Algeria and Australia as a browsing plant for cattle and sheep.

In tropical and subtropical areas (as close as the Mediterranean Sea), P. afra is suitable as a hedge plant.

The value of the plant for fodder precludes its use as a valuable source of paper pulp.

The leaves have a slight but pleasantly acrid flavor.  The soft foliage is relartively low in protein, with a moisture content which ranges up to 80 percent.  The nutritional composition of the leaves is otherwiseunknown. (Its herbaceous cousin, purslane, Portulaca oleracea L., fresh and unprocessed, has been analyzed and found to be a fair source of calcium, phosphorus, and iron for humans.  The Zulus use as infusion of Portulaca quadrifida L. as an emetic.)

 To Table of Contents
..


CONTAINERIZED

Larger trees will take full sun even in the summer in Sunset Zone 13, and can safely go without watering until the largest leaves start to show signs of wrinkling/dehydrating.  This occurs at first along the inside of the outer edge along the perimeter of the leaf, and then continues width wise.  Young leaves receive preferential nourishing by the plant and so rarely become dehydrated.  If a specimen has both old and new dehydrated leaves, it may have been too long without water to continue to survive.  Leaves becoming crisp and brown before falling off are a sign of the plant being too dry for too long. 

Leaves of plants grown in full sun are smaller than those of the same variety grown in partial shade.  Full sun is also known to bleach the leaves to a pale yellowish color on some large potted specimens. Brown patches on leaves can be due to sun scorch.  Move the affected plant to a more airy place and shade from the hot sun for two weeks.  Then, move back gradually over a period of two more weeks.

Too much water and/or fertilizer will cause leggy growth (up to 3 cm between nodes), as also will not enough full exposure to sunlight. P. afra appears to survive in almost any soil mix, and can go for several years without repotting.  It responds rapidly with improved color to moderate fertilizer or chelated iron.  A suggested fertilizing schedule using a balanced formula (e.g., 20-20-20) is weekly during the growing season(s), monthly during slow-growth times, none at all during winter.  A soil mix recommended in South Africa is three-quarters gravel or sharp stone and one quarter well-composted friable cow manure ("Krall" manure, dried and orderless).  Also recommended is a good loam-based No. 2 potting compost, or a soil-less compost, with 30% coarse, gritty sand.

Prune by pinching or cutting above a pair of pads.  In moderate to high temperature climates, a new bud will start within a week or two from the juncture of each of the pads, lighter green in color and emerging 90 degrees from the old leaves.  Several times new leaves have been observed arising from a previous pair which was only 2 mm in length, although usually the older pair is larger.  The new pair can be removed successfully as early as their bud is large enough to be plucked off using fingernails, approximately 2 or 3 mm long and not yet opened into a pair of leaves.  A new bud can arise from the base of a leaf before that leaf falls off.  Pruning above an older pair of leaves may result in a new bud at only one of them, and usually less quickly than if the pruning is done above a younger pair of leaves.  If only one leaf of an existing pair is removed, the resulting new growth just is less symmetrical.    However, leaving a stub of more than 1 or 2 mm in length, especially on older stems, can either delay or inhibit the growth of one or both of the new side buds. 

Adventitious buds can freely arise at nodes on old wood if the bark is intact there.  The timetable for this is highly variable and could extend into over a year before budding occurs if it is going to do so.  Wherever a bud or branch has been removed along a branch or the trunk a new bud could sprout. 

The non-budding stump of a cut-off large branch will eventually dry up and fall off by itself.  Branch stubs under 1.3 cm in length dry out and eventually will break off.  A bud may arise at the base of this at any time before or after separation.  The ends of stubs that are yellowish-brown to blackish-brown in color may have a slight non-spreading fungus.  It is recommended to keep the base of the plant free from litter build-up.  Larger stubs probably don't need special treatment or coverage, other than to not be directly watered (which might promote fungal growth).  The bark of the lower trunk and roots may get discolored with whitish, yellowish or brownish buildup from hard water deposits/mineral salts.  Leaves will also show hard water film if wetted directly.

Resembling a succulent, it is not considered able to be shaped into a traditional bonsai as defined by the Japanese school of the art.  However, very acceptable "artistic pot plants" can result from trained P. afraInformal upright or cascade are the two easiest styles in which to grow it.  Root-over-rock and raft are a couple of other successful styles in which this plant has been designed by enthusiasts outside of Japan. 

Use caution when wiring as the branches and leaf pads break easily.  It is recommended to leave the wire on to the point of apparently scarring the tree.  Once the wire is removed, the branch will bulge back into shape without disfigurement.  Branches can also be shaped using tie downs, spacers, and weights. 

Because of the nature of the thin skin and bark wood, the techniques of jin -- a weathered deadwood branch or apex -- and shari -- deadwood and/or hollow section along the trunk -- are not advised.

It can be used as an Indoor Bonsai where sunlight or strong artificial light is sufficiently available.  While lack of humidity is a plus for indoor specimens, good air circulation is still important.  Monthly feeding with a balanced (20-20-20) fertilizer is recomended.

Recommended pot colors include complimentary brown, gray, red or contrasting dark blue.

 To Table of Contents
.


BIBLIOGRAPHY

Bonsai, Bonsai Clubs International, December 1975. Vol. XIV, No. 10. Cover, color photo. Article on pp. 301-302. Given as 22" tall, informal upright potted in glazed dark blue container. The tree had been in training for ten years after being in a nursery where its 8 gallon nursery can had rusted away and the plant was covering a 25 sq. ft. area. Artist: James J. Smith. Plant was shown in Miami, FL at the "New Bonsai Horizons" Exhibition in July 1975.

Bonsai, BCI, February 1976. Vol. XV, No. 1. Cover, b&w photo of same tree as Dec. 1975. Caption on page 6. 

Bonsai, BCI, May 1983. Vol. XXII, No. 4. Cover, b&w photo of 8" mame size in a small Japanese container. The plant was in this pot for seven years. Photo provided by Mrs. Nikunj S. Parekh, Bombay, India. Caption on page 112. 

Bonsai, BCI, July/Aug 1986. Vol. XXV, No. 4. Pg. 16.  B&w photo from Houston Bonsai Society show.  Described as "elephant plant."

Bonsai, BCI, May/June 1991. Vol. XXX No. 3. Pg. 10.  Top right, small color photo captioned "Dwarf Jade Portulacaria afra by James J. Smith of Vero Beach, FL."  In the article "Succulents As Bonsai" by Jerry Kossler (pp. 9-10).

Bonsai, BCI, Sept/Oct 1993. Vol. XXXII, No. 5. Pg. 32.  Bottom left, a small color photo of a specimen shown at WBFF '93. Given as 24" high, 28" wide, informal upright, artist: James J. Smith, Florida. This does not appear to be the same tree as on Dec. 1975 cover, but probably is the same as May/June 1991.

Journal, American Bonsai Society, Winter 1994.  Vol. 28, No. 4.  Cover, color.  Caption on page 131 reads "Elephant Bush, Portulacaria afra.  This tree was propagated from a large cutting taken around 1985, and grown in an oversized nursery container for about three years.  In 1988, the artist, Jim Smith, pruned it back drastically and styled it as a multi-trunk bonsai.  The rock on which it is planted is a native limestone rock colected from a road construction.  It is presently housed in the Pacific Rim Collection in Washington State."

Journal, ABS, Fall 1999.  Vol. 33, No. 3.  Pg. 115.  Bottom right, a quarter page color photo.  Caption reads "'Elephant's Food' (Portulacaria afra) trained in the double-trunk style by Doug and Gail Acker of the Phoenix Bonsai Society.  The tree measures 25" in height, is ten years old, and has been in training six years.  This tree was given the President's Award by Bonsai Clubs International, and was selected at the [ABS '99] symposium exhibition by BCI past president Mary Bloomer and Chase Rosade, in Solita Rosade's absence.  (Photo by Hector Espinosa)"

                  Additional biographical details for Jacquin from http://www.nhm-wien.ac.at/nhm/Mineral/Jacquine.htm.

                  Additional  material courtesy of Prof. Gideon F. Smith, Director of Research, and his staff at the National Botanical Institute, Petoria, South Africa.

            Anecdote about John Naka and large tree told by Leroy Fujii to some members of the Phoenix Bonsai Society one evening during a meeting break at the Valley Garden Center entrance, c.1990.

                  Budding cut brought to RJB's attention by Paul Steele. 

                  Elephant diet details per Graaff-Reinet web site, http://www.graaffreinet.co.za/plant3.html

                  Geographical distribution map of Portulacaria afra in southern Africa.  Data extracted from the National Herbarium, Pretoria (PRE), Computerised Information System (PRECIS) as well as the Compton and Natal Herbaria.  (Map prepared by E.M.A. Steyn and G.F. Smith).

                  Information and questions as to fossil and early forms sparked by reply to e-mail from Mike Pippenger at Truman State Univerity in Missouri, Oct 9, 2000, asking about such things.

                  Meloidogyne Primer, http://www.extento.hawaii.edu/kbase/crop/Type/meloidog.htm

                  Names in current use for extant plant genera, entry for Portulacaria  Jacq., http://www.bgbm.fu-berlin.de/scripts/asp/IAPT/ncugentry.asp?name=Portulacaria

                   Royal Botanic Gardens, Kew, SEPASAL  project, http://www.rbgkew.org.uk/servlets/sepaweb

                Britannica Atlas; Chicago et al: Encyclopedia Britannica, Inc.; 1982.  Pp. 158-159, 220. 

                   The Marshall Cavendish Illustrated Encyclopedia of Plants and Earth Sciences; Bellmore, NY: Marshall Cavendish Corporation; 1988. Reference Edition Published 1990. Vol. 1, pp. 32-33, Vol. 4, pp. 424-425.

                The Natural Gardening Association Dictionary of Horticulture; New York: Viking; 1994.  Produced by The Philip Lief Group, Inc.  Published by the Penguin Group.  Pp. 430-431.

                    The New York Botanical Garden Illustrated Encyclopedia of Horticulture; NY: Garland Publishing, Inc.; 1981. Vol. 8, pp. 266-267.  After the genus name states "One of the two species...is commonly cultivated."  but only lists one species, afra

                 Oxford English Dictionary, Second Edition; Oxford: Clarendon Press; 1989.  Vol. XVI, pg. 186.

                    Sunset Western Gardening Guide, pp. 425, 512 of 1979 edition, and pg. 380 of 1967 edition.  Small black and green illustration of dubious identification value.

                    Taylor's Encyclopedia of Gardening; Boston: Houghton Mifflin Company; 1961. Fourth Edition. Pp. 88, 859, 964-965, 1296. 

Bailey, L.H. Manual of Cultivated Plants; NY: MacMillan Publishing Company; 1949. Revised edition. Pp. 364-365. After the genus name states "Two [sic] S. African fleshy shrubs or small trees...", but only lists one species, afra.

Branford, Jean  A Dictionary of South African English; Cape Town: Oxford University Press; 1980.  New Enlarged Edition.  Pg. 273.

Bredenkamp, G., Granger, J.E. & van Rooyen, N. 1996. Moist Sandy Highveld Grassland. In: Low, A.B. & Robelo, A.G. (eds) Vegetation of South Africa, Lesotho and Swaziland. Department of Environmental Affairs and Tourism, Pretoria.  Per http://www.ngo.grida.no/soesa/nsoer/Data/vegrsa/veg8.htm .

Brickell, Christopher (Ed.-in-chief)  The American Horticultural Society Encyclopedia of Garden Plants; New York: Macmillan Publishing Company; 1989, 1992.  Small color photo upper left pg. 121.  Text pg. 542.

Brookes, John and Kenneth A. Beckett & Thomas H. Everett The Gardener's Index of Plants & Flowers; New York: Collier Books, Macmillan Publishing Company; 1987.  Pp. 102-103.

Brown, J.R.  "The flowering of Portulacaria afra Jacq.," Cactus & Succulent Journal, Vol. XIX, 1947.  Pp. 140-141.

Burtt-Davy, J.  A manual of the flowering plants and ferns of the Transvaal, with Swaziland, South Africa; London; 1926.

Chidamian, Claude  The Book of Cacti and Other Succulents; New York: The American Garden Guild and Doubleday & Company, Inc.; 1958.  Pg. 131.

Clark, Randy   Outstanding American Bonsai; Portland, OR: Timber Press; 1989.  Bonsai #48 (color photo by Peter Voynovich) on pg. 121 is an "Elephant Bush."  This wired 17" cascade was in training at the time for 4 of its 7 years by Ruth H. Delaney, MN.

Court, Doreen   Succulent flora of Southern Africa; Rotterdam: A.A. Balkema; 1981.  Pg. 109, which states the genus has two species, and gives the second as "P.pygmaea (Ceraria pygmaea)."  Also is the source of the flowering in Vienna note. 

Dyer, R.A.  "Portulacaria afra," The Flowering Plants of Africa; 1978. 45: t. 1763.

Exell, A.W. and H. Wild (ed.)   Flora Zambesiaca;London: Published on behalf of the Governments of Portugal, The Federation of Rhodesia and Nyasaland, and the United Kingdom by the Crown Agents for Oversea Governments and Administrations; 1960.  Pg. 363.

Gillispie, Charles Coulston (editor-in-chief)  Dictionary of Scientific Biography; NY: Charles Scribner's Sons; 1980. Vol. 7, pp. 57-59.  None of the book titles listed for Jacquin contain any obvious references to Africa.

Graf, Alfred Byrd  Exotica 3: Pictorial Cyclopedia of Exotic Plants; Rutherford, NJ: Roehrs Company; 1957, 1959, 1963. B&w photos of varieties "aurea" (in Carlsbad, CA), "variegata", and unnamed on pg. 1395. B&w photo of unnamed green variety in the Transvaal, pg. 1396. B&w drawing of inflorescense on pg. 1471. Text on pg. 1697.

Griffiths, Mark  Index of Garden Plants; Portland, OR: Timber Press; 1992, 1994.  Pg. 925.  Derived from The New Royal Horticultural Society Dictionary.

Holttum, R.E. and Ivan Enoch   Gardening in the Tropics; Portland, OR: Timber Press, Inc.  ©1991 Times Editions Ptc Ltd.  Reprinted 1995, 1997, 1999.  Per pp. 240-241: "In the last few years, this plant has appeared in Malaysia...  Flowers are sometimes produced and these are small with pink petals."

Jacobsen, Hermann  A Handbook of Succulent Plants; Poole Dorset: Blandford Press; 1954.  English language edition 1960.  Vol. Two, pg. 745.

Killick, D.J.B. (ed.)   The Flowering Plants of Africa, Botanical Research Institute, Dept. of Agricultural Technical Services, 45:1763.  With illustration of flowering branch and four close-ups of flower.

Lamb, Edgar and Brian M.   The Illustrated Reference on Cacti & Other Succulents; Poole Dorest: Blandford Press; 1971-1977.  Second Edition 1971, Reprinted 1977.  Vol. 3, pg. 830 w/b&w photo.

Lesniewicz, Paul   Bonsai in Your Home; NY: Sterling Publishing Co., Inc.; 1994.  Color photo of root-over-rock style on title page, color of slant style on p. 154, and color of outer branch on p. 155 with care instruction text for "Portulacaria afra Elephant bush."

Lord, Ernest E.   Shrubs And Trees for Australian Gardens; Melbourne & Sydney: Lothian Publishing Co. Pty. Ltd.; 1970.  Fourth Edition.  Completely Revised 1964, Reprinted 1974 (Partial Revision 1970).  Pg. 301.

Lust, John  The Herb Book; NY; Bantam Books; © 1974, Benedict Lust Publications.   Pp. 501, 503, 505.

Martin, Margaret J. and Peter R. Chapman   Succulents and their cultivation; New York: Charles Scribner's Sons; 1977.  First published in U.S.A. in 1978.  Pg. 261 which states "The genus Portulacaria is monotypic, containing only P. afra...  The minute flowers are pale green." [sic]

McGourtey, Frederick (editor)  Handbook on Bonsai for Indoors; Brooklyn, NY: Brooklyn Botanic Garden. Fourteenth printing, Jan. 1985. Pp. 49, 63.

Medley Wood, J. and Maurice S. Evans   Natal Plants; Durban: under the Auspices of the Natal Government and Durban Botanic Society; 1899.  Vol. 1.  Pp. 63-64.  With five detailed line drawings of the flowers as Plate 78, "Drawn and described from specimens in flower on Berea, October, 1898.".

Miller, Mary J.  "Portulacaria afra, a succulent in tree form," Bonsai Today, No. 68, 2000-4, July-August 2000, pp. 39-44.  With seven color photographs by Jim Smith.  A very good article.  This also is the first published reference to this web site monograph (which was discovered after most of the article was written).  Note:  much of the information in the article that pertains to use as bonsai and which is also on this site originated in the article.

Moran, Reid  "Spekboom Blooms," Cactus & Succulent Journal, Vol. XLV, No. 1.  January-February 1973.  Pp. 71-73.  With three wonderful close-up photos of the flowers.

Oakes, A.J.  "Portulacaria afra Jacq. - a potential browse plant," Economic Botany, No. 27, pp. 413-416.

Palmer, Eve and Norah Pitman   Trees of Southern Africa; Cape Town: A.A. Balkema; 1972.  Volume One.  (First edition published in 1961)  Pp. 85, 113, 121, 290, 567-569.  B&w photos on pp. 124, 254 (thatched hut), and 566 (a large specimen in full and a close-up of its trunk).

Parekh, Jyoti and Nikunj Parekh   Wonderworld of Tropical Bonsai; Bombay: Vakils, Feffer & Simons Ltd.; 1984, 1987.  Cover is a color photo of a cascade specimen.

Perry, Bob   Landscape Plants for Western Regions; Claremont, CA: Land Design Publishing; 1992.  Pg. 251.  Color Plates 823 and 824, the latter showing many flower clusters.

Pilbeam, John   The Instant Guide to Healthy Succulents; NY: Times Books, a division of Random House, Inc.; ©1984 Eurobook Limited.  First American Edition.  Originally published in Great Britain in 1984 as How to Care For Your Succulents by Peter Lowe, London.  Pp. 70-71, with 4 color photos and drawings and two small b&w line drawings.  The first page states that the flowers "are similar to groundsel, yellow and daisy-like."

Rauh, Werner   The Wonderful World of Succulents; Washington, D.C.: Smithsonian Institution Press; 1984.  Translated by Harvey L. Kendall.  Pp. 133-134.

Shearing, David   Karoo, South African Wild Flower Guide 6; Kirstenbosch, Claremont: Botanical Society of South Africa in association with National Botanical Institute; 1994.  Pp. 68-69.  Includes illustration of flowering branch by Katryn Van Heerden.  Source of sweet eastern-northern and sour southerly-westerly aspects.

Sim, Thomas R.  The Forests and Forest Flora of The Colony of the Cape of Good Hope; Aberdeen, Scotland: under the Authority of the Government of the Cape of Good Hope; 1907.  Pp. 133-134.  With seven line drawings as Section II on Plate XIX.

Sonder, Otto Wilhelm  Flora Capensis; London: Lovell Reeve & Co.; 1862.  Vol. 2.  Pp. 385-386.

Trager, James   The People's Chronology; New York: Henry Holt and Company; 1992, 1994.  Pp. 244, 340, 390.

Van Wyk, Ben-Erik and Nigel Gericke  People's Plants; Pretoria: Briza Publications; 2000.  Pg. 74.

Watt, John Mitchell and Maria Gerdina Breyer-Brandwijk The Medicinal and Poisonous Plants of Southern and Eastern Africa; Edinburgh: E. & S. Livingstone Ltd; 1962.  Pg. 869.

Wu, Yee-Sun   Man Lung Artistic Pot Plants; Hong Kong: Wing-lung Bank Ltd.; June 1974.  Enlarged second edition.  Color photo #242 on pg. 257 shows a 61 cm tall specimen with thin surface roots in a short brown hexagonal pot on a carved black lacquered stand.  The caption describes the plant as "Crassula obliqua (Crassulaceae)," but to this researcher the plant is really a P. afra.
 
 

References Not Yet Checked include the following:

Aucamp, A.J., L.G. Howe, D.W.W.Q. Smith and J.O. Grunow.  1980.  "Die invloed van ontblaring op Portulacaria afra." Proceedings of the Grassland Soc. of Southern Africa, 15:179-184.    (In Afrikaans, with English summary.) 

Ras, A.M.  1990.  "Die invloed van ontblaring en vog op die tanienen polifenolinhoud van Portulacaria afra". J. of the Grassland Soc. of Southern Africa, 7:139-143.    (In Afrikaans, with English summary.) 
[Both citations per References section in Sustainability Indicators for Natural Resource Management & Policy, Working Paper 4, Natural Resource Management and Policy in Eastern Cape Province, South Africa: Overview Paper, edited by P.C. Lent, P.F. Scogings and W. Van Averbeke (Alice, South Africa: Agricultural and Rural Development Research Institute, University of Fort Hare, February 2000).] 
 

Guralnick, L.J., P.A. Rorabaugh, and Z. Hanscom, III. 1984. "Influence of photoperiod and leaf age on Crassulacean Acid Metabolism in Portulacaria afra (L.) Jacq."  Plant Physiol. 75:454-457.

Guralnick, L.J., P.A. Rorabaugh, and Z. Hanscom, III. 1984. "Seasonal shifts of photosynthesis in Portulacaria afra (L.) Jacq."  Plant Physiol. 76:643-646. 
[Both citations per SDSU Faculty Profile for Hanscom, Zac, III  http://www.bio.sdsu.edu/faculty/hanscom.html]
 

Guralnick, L.J. and I.P. Ting. 1986.  "Seasonal drought and rewatering responses in Portulacaria afra (L.) Jacq." Oecologia 70:85-91.

Guralnick, L.J. and I.P. Ting. 1987.  "Physiological changes in Portulacaria afra (L.) Jacq. during a summer drought and rewatering"  Plant Physiol. 85:481-486.

Guralnick, L.J. and I.P. Ting. 1988.  "Seasonal Patterns of water relations and enzyme activity of the facultative CAM plant Portulacaria afra (L.) Jacq."  Plant, Cell & Environment 11:811-818.

Guralnick, L.J., G. Goldstein, R.L. Heath, and I.P. Ting. 1992.  "Fluorescence quenching in the varied photosynthetic modes of Portulacaria afra (L.) Jacq."  Plant Physiol. 99:1309-1313.
[Four citations per Research Publications for G.L. Guralnick http://www.wou.edu/las/natsci_math/biology/gural/publications.htm]
 

Huerta, A. J. and I.P. Ting. 1988. "Effects of various levels of CO2 on the induction of crassulacean acid metabolism in Portulacaria afra."  Plant Physiol. 88(1):183-188.
[Citation per MU faculty profile for Alfredo J. Huerta, http://www.muohio.edu/~botcwis/bot/ah.html]
 

Lee, D.M. and S.M. Assmann. 1992.  "Stomatal responses to light in the facultative crassulacean acid metabolism species, Portulacaria afra," Physiologia Plantarum  85:35-42.
[Citation per PSU faculty profile for Sarah M. Assmann, http://www.bio.psu.edu/People/Faculty/Assmann/]
 

Zacharias, P J K  and G C Stuart-Hill, Proceedings of the First Valley Bushveld/Subtropical Thicket Symposium  (J Midgley;  Special Publication 1991), whose Part IV, Spekboom MiniSymposium, contains the following tantalizing topics:
"Adaption of Portulacaria afra to defoliation" by G C Stuart-Hill; 
"Aspects of the germination of Portulacaria afra(L.) Jacq." by  B H Whiting; 
"The influence of defoliation, irrigation and climate on the condensed tannin and total polyphenol content of Portulacaria afra" by A M Ras <same as above?>; 
"Spekboom dynamics" by  G P von Maltitz;
"How does spekboom survive drought?" by C W Stoltz;
"On the demise of spekboom in Natal's Valley Bushveld" by C R Hurt 
[Citation per http://www.ru.ac.za/institutes/rgi/gssa/specpu2.htm]
 
 

 To Table of Contents
.

This ongoing monograph was begun in the summer of 1993
and was first put on this web site in early July of 1999.
This work was last updated September 3, 2001.
If you have comments or thoughts concerning this, please e-mail me, rjb@phoenixbonsai.com


Home  >  Portulacaria   or   Home  >  Robert J. Baran  >  Portulacaria  or
Home  >  Phoenix Bonsai Society  >  Plants  >  Portulacaria