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ECOSCAPE NURSERYAloe polyphylla-Care & Cultivation 4.0 April 2008Congratulations, you have just purchased a very special plant which is threatened with extinction because of habitat deterioration due to the effects of overgrazing by cattle, sheep and goats. You may now participate in the salvation of an endangered species and enjoy its unique beauty. A.p. is also no longer able to reproduce itself because the bird which pollinates it is also endangered, the Malachite Sunbird. Viable seeds have few opportunities to find hospitable niches on the basalt slope because the flow of water regulated by the grasses, Themeda triandra-Festuca caprina, has dried up. The thick sod formed by these grasses functions like a sponge to regulate the flow of water downslope to the seedlings below, resulting in very few successful germinating seeds. Your new plant is grown from a seed produced by my hand pollination technique. This species is an obligate outcrosser. It does not self pollinate to produce viable seed. All natural progeny are hybrids the species is dependent on for plant performance. Others are now producing clones by tissue culture methods. These plants will be slow to develope, and without hybrid vigor. One of the characteristics which vary is the marginal dentation of the leaf. Your new plant is about 2 years old, 35-45 leaf count, and will quadruple in size to reach maturity to about 150-160 leaf be 14-16 high and 32-36 in diameter in about 5 years. There are five rows of leaf emanating from the center. A left hand spiral is described by pointing your left thumb at the center and matching any one row (sequence) of leaf with the curl of your fingers. A right spiral matches the curl of your right hand fingers in the same way. All leaf originates in the center and as new leaf is produced the older leaves are shoved to the outside of the row sequentially,with the oldest leaf being appressed to the soil surface and shaded. These leaves are retired by the plant; the goo is resorbed and used for other leaf and root tissue. Never attempt to remove any leaf just because it has some tip necrosis or looks bad. Remove only empty paper thin leaf from the underside. A.p. is bio-conservative and dynamic. The lifetime of a leaf on a mature plant is about two years. As new leaf appears in the center the plant twists clockwise or counter-clockwise to accommodate the spatial demands of the vertically oriented leaf. As the new leaf emerges a keel on the outside edge unequally divides it into a wide and a narrow section. The physical forces acting here produce a lateralization of the leaf, thus the spiral begins here. Right hand plants always have the narrow side on the right, and left hand plants always have the narrow side on the left. If you have trouble seeing the spiral orientation in your juvenile plant it is because of the lower number of leaf, be patient. Almost every customer I've dealt with can see it at the 50 leaf stage. The spiral orientation is not genetically determined. I have witnessed plants changing from R to L and from L to R. I have almost equal numbers of R and L plants in the inventory. Spiral phyllotaxy is a solution other plant species use to maximize photosynthetic capability (via leaf exposure) given their ability to mechanically support themselves. Acaulesence (without a stem) is a growth habit which imposes real challenges to plants in other Families, such as the Crassulaceae and Cactaceae. The biophysical solution is described by the Fibonacci equations. The maximum size of any acaulescent Aloe is related to the internal support the individual leaf get from the vascular strands and other fibers. A.p. leaf have virtually no internal support from fibers, only from vascular strands found just below the leaf surface. The rest of the leaf mass is goo. Pressure from the roots inflates each leaf to a turgid state and this gives A.p. its form and drives new growth. A.p. biomass is about 95% water. Storage of starch (the fuel) is diffuse in A.p. leaf. In other woody plants starch is stored in parenchyma tissue. The translocation distance from leaf to root through the crown is short. A.p. can rapidly move goo to the roots and water from the roots to the leaf. The crown zone is a tightly packed mass of vascular stands, where leaf vessels connect with root tissue vessels. A.p. is a dynamic plant which reinvents itself continuously by retiring old leaf and roots, and using its goo to produce new tissue, almost in the same space. You cannot induce new leaf to form by adding fertilizer to an adult plant without witnessing the senescence of the oldest leaf. One consequence of diffuse starch storage within the leaf is on flower production. To produce an inflorescence the size of deer antlers requires a lot of energy. A minimum leaf count required for flowering is about 90 leaf. This physiological feat requires the expenditure of several leaf.Plants may not repeat flower the next year and they rarely flower at all and then do not accept their own pollen. A.p. is an obligate out-crosser. It co-evolved with the pollination services of the Malachite Sunbird. I believe A.p. is very young species, only appearing in the Drakensberg and Maluti mountains of Lesotho in the last 25,000 years. A.p. is found at elevations of 7500-8500 ft. at 29-30 degrees South latitude where cold, dry winters with nightly lows of 10-15 F alternate with daily highs of 30-40 F. The summer weather is mild with 30-40 inches of rainfall from thunder storms. Some cyclonic storms in winter from the Cape drop 3-6 of snow in the Malutis mountains. The following recommendations for plant management are very broad. Specific site microclimates will always rule over regional advice. For USDA zones 1-9a juvenile plants should be brought inside and protected from hard freeze conditions. Indoors you must provide a gro-light on a timer to give 6-8 hours/day of of light with sufficient long wave ultraviolet to maintain the plants form. Without a gro-light leaf length and width increase and the rosette form opens up. The spiral form is dependent on shorter wavelengths of light, which is plentiful at higher elevations. I suggest a small fan and never let your plant go dry. Cooler temperature are better, 40-60 F is OK. The adult plants are more tolerant of extreme temperatures than the juvenile plants. To cultivate A.p. in low desert areas with 100+ F summer temperatures do not use black plastic containers, ceramic is best to insulate the roots against high temperatures. Morning sun is OK but shade in the afternoon is necessary. I sometimes stretch 70% shade cloth over the plants. Use high quality water only, not salty or alkaline. Acidic soil mixes are beneficial. During high summer temperatures A.p. will not grow, withhold fertilizer until the Fall. Understanding root physiology is important to successfully grow A.p. The bright yellow roots with white hairs have high oxygen demand. At high soil temperatures (90+F) the rate of respiration races beyond the soils ability to breath and deliver oxygen, so root tissue begins to die by suffocation. You can kill root tissue in two minutes by dropping it into 90F water. A physiology like this places A.p. just to the right of Cymbidium orchids on a scale which arranges plant root oxygen demand; with orchids on the left (highest O2 demand) and plants such as Bald Cypress (Taxodium) on the right. Proper combination of temperature, water availability and soil particle size enable the roots to function like a pump, to inflate the leaf fully. The first check on plant health is the turgidity of the leaf. A good soil mix for container A.p. will start with any good potting soil free of pest and diseases to which orchid bark chips are added to about 50% volume. These will be digested by actinomycete fungi in 3 years though. A longer lasting additive for permanent container plants will be pumice or red lava 5/16 or 3/8 grade. I use #3 or#4 perlite in the soil mix to about 30% volume. I use vermiculite also. Landscape A.p. will develop best on top of a sandy loam soil with free root run (i.e., no competition). The roots are very aggressive and will explore the soil volume wherever physical conditions permit. When in doubt select a larger container than you might suspect. An adult plant can be raised in a half-whiskey barrel. Confined roots which circle and girdle other woody plants are not a problem for A.p. In the genus Aloe leaf propagation is not possible. You must have a stem section, seed, utilize tissue culture methods, or have offsets. Occasionally a plant splits growth centers. Wait for about two years before attempting to separate the plants. Let this happen naturally. Once separated you may clean the under-crown with a water jet, and use some root hormone to help new roots form. Place the plants in some shade and use compost for media. If the leaf collapse and the rosette close pull your plant up and jet wash the under-crown of all dead root tissue. To grow new roots place the plant on moist mini orchid bark or coif fiber in a shaded place. I about 4 weeks a new set of roots will enable you to replant it. Aloes are attractive to Homopteran insects such as aphids, and mealy bugs, which may be farmed by ants. Aphids are able to tap a vein on the abaxial side of the leaf. Thrips, nematodes and some small beetles may chew roots and under-crown tissue. A preventive program of insecticide application will be a life insurance policy for A.p. Use 1% chlorpyrifos granules, .5% permethrin solution or 1% diazinon granules and water wash it into the soil. The only fungal pathogen which will kill A.p. is Fusarium oxysporum. A foliar infection with purple and sunken lesions is usually not fatal and can be stopped with full sunlight, the ultraviolet component will kill fungal mycelium. If Fusarium infection occurs on the roots it will create a purple lesion and kill that tissue. If chewing insects create a court of infection at the under-crown then Fusarium may kill the plant rapidly. Some fungicides which will stop or suppress Fusarium are Captan, Benlate, C3336, Medallion. You could also use Physan 20 or Phytar as a soil drench to prevent this. If you need more explicit information please use E-mail to describe the problem, send a picture to id the problem. Alan C. Beverly |
