Bismarckia is a monotypic genus in the palm family, containing only one species, Bismarckia nobilis. It is endemic to western and northern Madagascar, an island well known for its rich diversity of unique palms, with Bismarckia being only one of the approximately 170 species of palms found here, of which 165 are endemic, meaning they grow wild only in Madagascar.
The Bismarck palm can be found in the plains of the central highlands, nearly reaching the western and northern coasts, favouring savannas of low grass, usually in lateritic soil. Laterite soil is rich in aluminium and iron, formed in wet and hot tropical areas. Almost all laterites are rusty red due to the presence of iron oxides. It is prepared by the long-lasting and intensive weathering of the parent rock.
As much of this land has been cleared with fire for agricultural use, Bismarckia, along with other fire-resistant trees like Ravenala madagascariensis and Uapaca bojeri are the most conspicuous components of this arid region of Madagascar.
The genus Bismarckia is named for the first chancellor of the German Empire, Otto von Bismarck, and the epithet for its only species, nobilis, comes from Latin for 'noble'. And noble it certainly is, and today Bismarck palms are grown throughout the tropics and subtropics under favourable microclimates. They are planted in many parts of Indonesia and Australia, and in the United States they are planted in several areas of Florida, a few areas of Southern California, southern and south eastern Texas, and southern Arizona.
The evergreen Bismarckia nobilis grows rather slowly when young, but once it starts developing a trunk, growth rate is more moderate. Over time it will develop a thick solitary trunk with a diameter of around 30 to 45cm, with a slight bulge at the base. It is grey to tan in colour and shows ringed indentations from persistent old leaf bases, which are split, creating an attractive pattern on the trunk. In their natural habitat these palms can reach over 25 meters in height, but usually get no taller than 9 to 12m in cultivation, with a spread of 3.5 to 5m. Outside of the tropics and subtropics this palm will generally remain a lot smaller.
The solitary trunk is adorned with a broad, nearly-spherical leaf crown of intensely steel-blue, fan shaped fronds about 120cm long and wide, but at maturity they can become enormous, with a single frond reaching up to 3m in width. The leaves are classified as costapalmate leaves, which are intermediate between pinnate and palmate leaves, with the overall leaf blade being round to oval in shape. Leaflets are joined together for some, or most of their length, but are attached along a costa, which is an extension of the petiole into the leaf blade. The leaves produce a wedge-shaped hastula where the blade and petiole meet. Petioles are 2 to 3m, slightly armed, and are covered in a white wax, as well as cinnamon-coloured caducous scales.
Although most cultivated Bismarckia feature steel-blue foliage, a green form exists, but this one is less hardy to cold.
These palms are dioecious with separate male and female trees. The trees produce pendant inflorescences of dark brown flowers, and in female trees the flowers are followed drupes of olive-brown fruits about 3cm across.
Uses:
All over Tropical Africa, and especially where palm species are cultivated, the beetles and larvae of the African palm weevil (Rhynchophorus phoenicis) are widespread and recognized pests of the palm species they feed on. The large beetles pose a very serious threat to plantations of oil palms as they feed on the shoots and young leaves, and their larvae excavate tunnels in the trunk, frequently leading to the death of the host plants.
The edible larvae can reach a body length of about 25mm, and are widely consumed in Africa, especially in Ghana where they are locally called “Asomrodwe” or “Akokono”, and elsewhere in Beti communities of the central and southern regions of Cameroon, the larva is locally called “fos”.
“Entomophagy” which literally refers to consumption of insects and their products, has been identified as an emerging solution to improving global food security, and Rhynchophorus phoenicis larvae are currently being studied to discover their full nutritional value, and to determine how economically viable they would be for generating a livelihood for locals from insect farming. Today we know that a single 100 gram serving of African palm weevil larvae contains: 485.44 Calories, 37.57g of Protein, 22.82g of Fat, and 32.38g of Carbs.
Click here to see Google images of Rhynchophorus phoenicis beetles and their larvae
Other uses for the Bismarck palm include, emptying the trunk of its pith and then flattening the bark to use as planks, or in partition walling. The leaves are used for roofing and basketry, and the pith is served as slightly bitter sago.
In the Garden & Home:
With their great height and majestic presence, Bismarck palms deserve to stand alone as the focal point of your landscape, so site them either singly or in groups in large expanses of lawn, or in the centre of a lush and colourful tropical garden where their stout trunks and gorgeous canopies can be the main attraction. They are also unforgettable if planted in rows alongside long driveways or walkways.
As part of a lush informal landscape designed for a dense privacy screen, pair the Bismarck palm with small to medium sized flowering shrubs and shade trees.
This palm is perfect for large public parks or office parks, parking areas and all large commercial landscapes where they can be maintained correctly, and where their large stature can be used to showcase modern architectural lines.
All palms have fibrous root systems that are not invasive, but because of their massive crowns, the Bismarck palm needs plenty of room in a landscape area, and should not be planted very close to walls or buildings. It can be overpowering and impractical in small residential landscapes, so for smaller spaces, consider planting it a large pot.
The Bismarck palm will bring a touch of the tropics into your home or office, and in tropical climates it is used in shopping malls and other large buildings which have natural sunlight. It is known to help purify the air indoors by removing toxins such as benzene, formaldehyde, and carbon monoxide.
Cultivation/Propagation:
The Bismarck palm is easy to cultivate and care for in the right environment, and today it is grown throughout the tropics and subtropics. In these climate types the tree grows the quickest and the biggest, however in these same regions, if it is cultivated along the coastline it will grow significantly more slowly and with less intense coloration.
It is highly tolerant of intense inland heat, but also does well in coastal areas as it is moderately tolerant of salt spray on its leaves. It also does very well in Mediterranean climates like our winter rainfall regions, but it never looks quite as majestic as it does in a more tropical climate.
In tropical climates the green form is much faster growing than the blue form; however, the opposite tends to be true in a Mediterranean climate. In fact, in most such climates, the green form is known as a very marginal palm, often unable to tolerate much freezing weather at all, and sulking dramatically in prolonged cool seasons. In fact, its culture is so different from the blue-silver forms, that it seems like a totally different species. Therefore, it is very rare to see this colour form growing in a Mediterranean climate, and even rarer to see one in such a climate that is healthy looking.
Because this species is not as resistant to windstorm damage as most other species of palms, it will look at it best on a more sheltered site.
While the Bismarck palm has an exceptional tolerance of intense, dry heat and is perfectly adapted to low desert areas, it really thrives and grows much larger in areas with adequate rainfall.
Although this palm will suffer from cold damage, it will quickly recover, but it’s best to cover small plants, which can be damaged by temperatures below -2°C. The green variety is sensitive to cold and damaged at 0°C, but the silver-grey variety will tolerate -3°C, and as it matures its cold tolerance seems to improve dramatically, with some palms surviving temps down to -5.55°C with only moderate leaf damage.
The Bismarck palm loves full sun but will take part shade. It is tolerant of a wide range of well-drained soils, including sand, loam, and clay, and can adapt to either acidic or alkaline soil. Good drainage is vital, as this palm is susceptible to root rot.
To plant, dig a square hole that is wider and deeper than the root ball of the plant. Remove the plant from its container, place in the hole and backfill with soil, ensuring that the tree is planted at the same depth it was growing in its original container. Avoid planting palms too deeply, as oxygen needed for potassium uptake decreases with soil depth, and planting the Bismarck palm too deep can lead to many other problems too, as it is susceptible to be eaten by microorganisms that live naturally in soil and other mediums. Large plants may need to be staked at first, but be very careful that the stake or the ties do not hurt the stem.
To help the roots establish after planting, it’s essential to water young trees regularly and its best to water directly into the root system or sprayed through the palm heart. Moderate watering thereafter during prolonged hot and dry spells will keep it looking at its best.
It makes sense to feed your palm trees on a regular basis. They need a good quality fertiliser that meets all their essential needs. Choose a balanced NPK fertiliser (N for Nitrogen, P for Phosphate, and K for Potassium), and using a fertiliser that contains micronutrients, like iron, boron and manganese would be best. Generally a ratio of 3:1:3 is recommended for palm trees, but because this is not readily available for gardeners in South Africa, good alternatives would be 5:1:5 or 3:1:5, as these fertilisers are high in nitrogen and potassium. If your fertiliser does not contain micro nutrients, feed with a trace element mixture like Trelmix occasionally to ensure perfect growth.
Growing the Bismarck Palm Indoors:
This is a magnificent palm for large indoor spaces, and its slow growth habit means it can thrive indoor for many years with the right care, reaching great proportions, depending on the pot size.
Being a tropical plant, it thrives in warm and humid environments and should therefore be situated in a warm room that gets bright natural light or direct sunlight for a good part of the day. Too little light will cause the plant to grow slowly and it will lose its distinctive colour. And too much sunlight may scorch the leaves. In dry inland areas you may consider investing in a humidifier for the room where your palm is growing, or you can spray the foliage down regularly with a fine mister. This palm is not a good choice for rooms or offices lit only by artificial light.
Avoid exposing the plant to extreme temperature changes, such as drafts or air conditioning vents, which can cause stress and damage to the leaves. Ideal indoor temperatures should never drop below 18°C but can be higher.
The Bismarck palm is not very particular as to soil type or pH but prefers a well-drained, slightly acid soil, so a good potting soil mixed with generous quantities of palm peat and some perlite should work just fine. Water regularly as required during the warm season and less in winter. However, be careful not to overwater, by allowing the soil to dry out slightly between watering’s, and never allowing the pot to stand in a drip tray full of water. Frequency of watering will be determined by the size of the pot and also its location, so in warm sunrooms it will need more watering than in cooler rooms. Feeding regularly in summer with 5:1:5 or 3:1:5 fertilisers that are high in nitrogen and potassium, and supplementing with a trace element mixture like Trelmix occasionally will ensure perfect growth.
If you decide to start with a small palm, it’s not a good thing to plant it directly into a very large pot, rather put it into a smaller pot and repot ever 2 years or so in spring into one that is one or two sizes bigger. If the root ball is tangled or bound, gently loosen the roots and trim off any dead or damaged roots before repotting with fresh potting soil.
Signs of overwatering can lead to root rot, and symptoms may include yellowing or wilting leaves. Signs of under watering may include dry, brown leaf tips, drooping or wilting leaves, and also yellowing of the leaves.
When grown indoors this palm may be susceptible to common houseplant pests such as spider mites, mealybugs and scale insects, which can be treated with a suitable insecticide.
How to Trim Bismarck Palms:
Palm trees grow vertically, with new leaves sprouting from above as the trees get taller. When the old leaves die, the leaf base becomes part of the tree's trunk, which is what causes the scarred pattern that's typical of palm trunks. Because palms have unique nutritional requirements and they tend to recycle many of their nutrients from older growth to newer growth, over-pruning can result in nutrient deficiencies, and especially potassium deficiency. When pruning palms, only spent flower stalks, immature fruit, and brown fronds should be removed.
Technically, you can trim your palm tree any time or season of the year, and if you want your tree to enjoy the best health, it’s usually only necessary once or twice a year. Try to keep trimming to a minimum in mid-summer when it is very hot, as it may be more challenging for the tree to recover and thrive at this time.
Because palms cannot repair wood tissue, they are more susceptible to diseases when their trunks are damaged, so it is vital that you do not damage the trunk of your palm when trimming.
Take your safety into account when you're trimming a palm or any other type of plant. Safety gear like gardening gloves and goggles can be helpful in protecting your hands and eyes. You must also protect the safety of your tree by sanitizing the blades of your cutting tools to help prevent the spread of disease. You can do this by thoroughly cleaning your lopper or pruning saw, then dipping or wiping their blades with rubbing alcohol, which doesn't need to be rinsed off prior to use.
Select fronds that are hanging downward and are clearly dead and brown all the way to their bases. Cut the frond parallel to the palm's trunk, and to prevent damage, keep it about 5 to 8cm from the trunk. Remember that evenly spaced leaf scars are a natural feature of a palm tree and can't be trimmed away without harming your tree.
Because damage to the trunk can be fatal, also remember to keep lawn mowers and weed-eaters well away from them.
When the trees are still small, trimming can easily be done at home with loppers or a saw, but once the palms mature, reaching the canopy will be impossible for the average gardener to achieve, and the services of a specialist palm pruner will be essential.
Transplanting:
Mature field-grown specimens are more difficult to transplant than most other species of palms, however, landscapers have achieved reasonably good transplant success by root-pruning the palms several months prior to moving them, and by digging out unusually large root balls, or by removing all of the leaves at the time of moving.
Propagation:
Bismarck palms are propagated by seeds that germinate within six to eight weeks at high temperatures between 32 to 37°C. The seedlings are ready to plant when they develop a second set of leaves. They grow rather slowly when young but once they develop a trunk, growth rate is more moderate.
Soak the seeds in a thermos filled with hot water for two days at 30°C. Prepare small pots with an equal combination of coarse sand and standard potting soil. Moisten the soil before lightly pressing one seed into each pot, about 2.5cm deep. Keep the pots in a shaded, warm spot. Check the soil daily and add water as needed to keep it moist.
Problems, Pests & Diseases:
If grown correctly Bismarck palms do not suffer from many serious pest or disease issues. However, like all vegetation, they are vulnerable to pests and diseases. Spider mites, mealybugs, and scale insects are some of the most common pests that can harm palms. These pests can cause major harm to the plant and even kill it if left unchecked.
To handle insect infestations on small trees is as simple as spraying with an appropriate pesticide for the problem, however tall, mature trees are not that easy, and will require specialist equipment to ensure a full cover spray; or alternatively, systemic pesticides can be applied around the roots.
Spraying with organic insecticidal soaps like Biogrow: Neudosan is effective against many soft-bodied insects, including scale, aphids, mealy bugs, and mites. Biogrow: Bioneem is another powerful insecticide; and Biogrow: Pyrol has naturally occurring plant oils as its active ingredients and kills all stages of insects, as does Margaret Roberts Organic Insecticide.
You will need to apply the remedies as a full cover spray, and repeat applications will be required if infestations are severe. Adding G49 wetter/sticker assists in breaking down the protective shell of some scale insects and helps the remedy stick better to the leaves and trunk of the tree.
Systemic solutions are applied to the roots of plants and are quickly absorbed by the plant to control various insect pests. Koinor is a systemic insecticide for the control of various pests; and Insecticide Granules Plus is a ready-to-use systemic insecticide in granular form, which is effective against most sucking insects, and provides long term control, between 4 to 8 weeks.
African Palm Weevil
Click here to see Google images of Rhynchophorus phoenicis
In tropical regions the Bismarck palm is susceptible to the African Palm Weevil or Rhynchophorus phoenicis. African Palm Beetles can reach a body length of about 25mm and are considered a serious pest in oil palm plantations. The life cycle of the African Palm Weevil is similar to that of other Rhynchophorus species. The adult beetles feed on the shoots and young leaves and lay their eggs in wounds in the leaf bases, or in the stems of dying or damaged parts of palms. After hatching, the weevil larvae excavate tunnels in the trunk, frequently leading to the death of the host plants.
Palms infested with Rhynchophorus may show a number of collapsed leaves hanging along the trunk. In severe infestations, the entire crown of a palm may fall over or drop off due to extensive burrowing by the larvae. Older leaves can easily be pulled out, revealing damaged petioles and leaf bases
The larvae of this palm weevil are edible, and the species is widespread throughout tropical and equatorial Africa, from Senegal to Ethiopia, Nigeria and South Africa.
Ganoderma Butt Rot
Click here to see Google images of Conk or fungal fruiting body of Ganoderma on palms
Like all palms, the Bismarck palm is susceptible to Ganoderma butt rot. The fungal genus Ganoderma is a group of wood-decaying fungi that are found throughout the world on all types of wood—gymnosperms, woody dicots, and palms, and there are many different species of this fungus. Ganoderma butt rot is fatal for Palms, so prevention is vital, and the palms seldom show more than a slow decline with stunted growth and discoloured, wilting leaves, until the disease reaches its final stages.
This soil-borne white-rot fungus causes an internal discoloration and decay of the trunk, which is generally confined to the bottom 90cm to 1.2m of the trunk, destroying the palm’s lignins and cellulose, and eventually disrupting the nutrient-transporting xylem tissue. Once about 85% of the cross sectional area of the trunk has been destroyed by the fungus, the canopy may show signs of wilting or other water stress symptoms, followed by fairly rapid loss of the lower leaves, and eventually the death of the palm.
Fungal fruiting bodies called “conks” may emerge from the lower portion of the trunk prior to the death of the palm. Initially they look like hard marshmallows, but eventually they become woody, shelf-like structures with a brown top and white bottom. These conks can produce billions of reddish-brown dust-like spores that will blow everywhere, spreading the disease. Thus, while there is no control for this disease, removing conks in the early stages of their development can reduce its spread.
Be sure to remove or grind the stump after cutting down any palm to prevent Ganoderma conks from growing and reproducing on the stump. Some palms, however, never develop conks, and the only way to diagnose Ganoderma accurately is to cut down a declining palm and examine the trunk.
Potassium (K)
Click here to see Google images of Potassium deficiency in palms
Potassium (K) is one of the key elements necessary for palm health and is required in relatively large amounts. There are two primary symptoms of this deficiency: Light-coloured or brown necrotic speckling of the leaves; and scorching of the leaf tips or margins can occur. The extent of the speckling and scorching depends on the severity of the potassium deficiency. Some species of palms may develop translucent orange and yellow spots, while others develop necrotic spots or yellowing of the leaves.
A deficiency of potassium also results in a condition called "frizzle top" which causes leaves to look frayed and torn. And when the frizzling of the leaflets is at the ends of the oldest leaves, this is indicative of Potassium (K) deficiency.
Potassium tends to leach rapidly from sandy soils, and it is in these soils that potassium deficiency is more apt to occur. In heavier clay soils, the rate of potassium leaching is reduced. Potassium deficiency can be prevented and/or be treated with correct fertilisation.
Palms in lawns may become potassium deficient as many turf grass fertilisers are high in nitrogen but low in potassium. Palms need fertilisers that contain potassium as high as, or higher than the nitrogen content. Fertilise palms growing in lawn separately from the turf.
Avoid cutting leaves that are only partially dead, as these are serving as a supplemental source of potassium to the palms.
Manganese (Mn)
Click here to see Google images of Manganese deficiency in palms
Manganese deficiency has been reported on Bismarckia, but it is not common. Manganese deficiency can be fatal to palms, and is a common problem in high pH soils above 6.5, because manganese is insoluble at high pH levels. Additional causes can be high water tables or poor drainage, and excessive amounts of soil phosphorus which tie up certain micronutrients, particularly manganese.
Early symptoms of manganese deficiency are interveinal chlorosis (yellowing between the veins) and upon closer examination you will see longitudinal necrotic streaking on the chlorotic (yellowing) leaflets. If the deficiency is advanced, frizzling of the leaflets at the base of the youngest leaves is apparent.
To know if it’s a Potassium or Manganese deficiency, you need to observe if the frizzling occurs on the base of the leaves, or on the tips. From a distance they may appear identical, and it’s not unusual to see both manganese and potassium deficiencies on the same palm or even on the same leaf.
Advanced symptoms of manganese deficiency also include a reduced canopy size and smaller trunk diameter, also known as "pencil-pointing". This condition can be corrected by spreading Manganese Sulphate on the soil beneath the palm, and watering it in well. The amount you use will depend on the size of the tree, and for mature specimens between 450g to 1kg of manganese sulphate can be spread out as far out as the canopy reaches.
Using a liquid or granular fertiliser which contains trace elements will help to correct deficiencies.
Volcanic Basalt Rock Dust is an organic amendment designed to enhance the quality of your garden soil. This dust is derived from finely ground basalt rock, which is rich in nutrients, minerals and trace elements essential for plant growth.
Trelmix is a trace element solution which promotes growth and corrects chlorosis (yellowing), blotching and stunting where these are due to trace element deficiencies. It is not a whole fertiliser and should be used in addition to other basic fertilisers. Trelmix can be applied as a foliar feed, which is easy for treating small palm trees, or as a soil drench, which is best for mature palm trees, but could work out very expensive.
Magnesium (Mg)
Click here to see Google images of Magnesium deficiency in palms
Magnesium deficiency in the soil is occasionally observed in Bismarckia nobilis, as magnesium is readily leached from sandy soils and other soils having little cation exchange capacity. Cation exchange capacity (CEC) is a measure of the total negative charges within the soil that adsorb plant nutrient cations such as calcium, magnesium, and potassium. As such, the CEC is a property of a soil that describes its capacity to supply nutrient cations to the soil solution for plant uptake.
Although magnesium deficiency is never fatal in palms, it is the central element of the chlorophyll molecule necessary for perfect plant health. Symptoms of this deficiency appears on the oldest leaves of palms as broad chlorotic (yellow) bands along their margins with the central portion of the leaves remaining distinctly green.
Frequently, magnesium and potassium deficiencies coexist on the same palm, the oldest leaves will show typical potassium deficiency symptoms, while magnesium deficiency symptoms will be visible on mid-canopy.
Although some slow-release fertilisers contain micronutrients, and products like Trelmix provide all the micronutrients a plant requires, a quick treatment with Epsom salt for a yellowing palm tree will certainly help because it is water soluble and will work quickly.
Combined with regular fertilising, Epson salt can be beneficial for palms, but using too much will cause potassium problems. High levels of nitrogen, potassium or calcium in the soil can also induce or exacerbate magnesium deficiency, so feed your palm correctly, and in the right quantities.
The amount of Epson salt you use will depend on the size of your palm tree, and for fairly mature trees you will need to sprinkle 1 to 1.5kg under the tree’s canopy, then water it in well.
Boron (B)
Click here to see Google images of Boron deficiency in palms
Various leaf distortions on otherwise dark green new leaves are caused by Boron (B) deficiency. Boron deficiency can cause puckering, crumpling, truncation, incomplete opening, twisting, or stunting of the new leaves, or it may cause the palm to branch or grow sideways, or even downwards.
The malformed new growth is caused by the lack of just a tiny amount of an element called boron, a micronutrient. Boron is associated with cell division and cell production in buds and root tips. Because this element is water soluble, it appears to leach faster than the palm roots can pick it up, especially in sandy soils, and during particularly rainy periods, or if over-irrigated.
Normal growth may resume once the heavy watering events cease, but in some situations additional boron may need to be supplied or the palm will die. The “feather” frond palm group is more prone to boron sensitivity than the fan (palmate) shaped frond group.
Some symptoms of Boron deficiency could be confused with those of manganese (Mn) deficiency. However, boron deficiency symptoms tend to be worse at the leaf tips, while manganese deficiency symptoms are more severe towards the base of the frond. Boron deficient leaves are also usually not chlorotic (yellowed) as manganese and iron deficient new leaves are.
Because there is a fine line between correction and overdose (death) with Boron, treatment must be approached with caution, and a specialist may be required.
Using a liquid or granular fertiliser which contains trace elements will help to correct deficiencies.
DynaGro is a ready-to-use, liquid fertiliser, suitable for all kinds of plants, and contains all the required trace elements.
Volcanic Basalt Rock Dust is an organic amendment designed to enhance the quality of your garden soil. This dust is derived from finely ground basalt rock, which is rich in nutrients, minerals and trace elements essential for plant growth.
Trelmix is a trace element solution which promotes growth and corrects chlorosis (yellowing), blotching and stunting where these are due to trace element deficiencies. It is not a whole fertiliser and should be used in addition to other basic fertilisers. Trelmix can be applied as a foliar feed, which is easy for treating small palm trees, or as a soil drench, which is best for mature palm trees, but could work out very expensive.
Warning:
Bismarckia nobilis isn’t invasive or toxic for pets and humans, but keeping children away from female plants when the flowers ripen to become fruit is a good idea, as the fruit may look appetizing to small children, and while it’s not toxic, the fruit contains a hard seed, which may pose a choking hazard. Also be aware of the sharp, pointed leaves that can be harmful to young children or pets.