The taxonomic history of Prunus is long and complicated, in part due to the economic value of its fruit crops and also the ease with which some species hybridize. Here, Prunus is circumscribed in its broad sense based on the argument that when viewed on a worldwide scale, the morphologic discontinuities among the segregate genera diminish and they overlap with one another. Included here are species that have at times been placed in the genera Amygdalus, Armeniaca, Cerasus, Laurocerasus, Padus, and Persica.
At the species level, Prunus has been the object of the usual combining and splitting common among taxonomists with different philosophies and opinions. In particular, over-reliance on the indument of various vegetative and floral parts has led to the naming of numerous species and infraspecific taxa. Similarly, too much has been made of fruit colour and palatability in naming taxa of Prunus. It is very likely that, as molecular and genetic data are analyzed and, more importantly, correlated with morphological data, circumscriptions will be redrawn and the number of Prunus species will be reduced[
Amygdalus glandulosa Hook.
Amygdalus texana (D.Dietr.) W.Wright
Prunus glandulosa (Hook.) Torr. & A.Gray
Common Name: Texas Peachbush
Prunus texana is a much-branched, sometimes weakly spiny, deciduous shrub growing 50 - 150cm tall. The plant sometimes suckers and can form small thickets[
The plant is harvested from the wild for local use as a food. It can be used in soil stabilization projects and is also of value in breeding programmes for the Japanese plum.
The Edwards Plateau where Peachbush occurs is threatened by development due to the rapid growth of the urban settlements of San Antonio, San Marcos, Austin, Round Rock, and the suburbanizing areas around them. Further west, many formerly rural areas have become retirement communities or vacation resorts. Outside the urban areas large ranches are being replaced by ‘ranchettes’ of 1 - 20 acres. As Texas is predominantly privately owned, most land is not protected from development. Fire, as a land management strategy, is used less and less as housing density increases. The increasing population causes more use of recreational areas, which tends to degrade the quality of the habitat for conservation. Invasive species are also a likely threat from resident's gardens. Edwards Plateau is highly fragmented due to the overgrazing currently occurring, fire suppression and urbanization. The plant is classified as 'Near Threatened' in the IUCN Red List of Threatened Species(2013)[
The plant (especially the seed and young shoots) contains cyanogenic glycosides, especially amygdalin and prunasin. When injested, these compounds break down in the digestive tract to release cyanide. Used in small quantities in both traditional and conventional medicine, this exceedingly poisonous compound has been shown to stimulate respiration, improve digestion, and promote a sense of well-being[
]. It is also claimed by some to be of benefit in the treatment of cancer - though this claim has been largely refuted.
In larger concentrations, however, cyanide can cause gasping, weakness, excitement, pupil dilation, spasms, convulsions, coma and respiratory failure leading to death[
The fruits and flowers of most members of this genus generally have low or very low concentrations of this toxin, though the seeds and young shoots can contain much higher levels.
The levels of toxin can be detected by the level of bitterness:- for example sweet tasting almond seeds are a major food crop and are often eaten in quantity, whilst bitter tasting almond seeds are used as a flavouring (in marzipan for example) but are not usually eaten on their own.
In general, it can be considered safe to eat any fruit or seed from species in this genus that either have a sweet flavour or are slightly bitter. Great caution should be taken, however, if the flavour is moderately to very bitter[
Southern N. America - Texas
Deep sand, plains and sand hills, grasslands, oak woods; at elevations up to 200 metres[
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The plant is found in the wild on poor or disturbed soil which is of neutral or alkaline pH. The soil tends to be well-drained, sand or sandy loam (but not limestone). It develops a deep root system and is drought resistant. It thrives in direct and partial sunlight, is highly heat tolerant[
The plant blooms in spring with its fruit ripening in early summer[
Despite the peachlike fruits of this plant, DNA evidence supports its placement among the native American plums[
Most members of this genus are shallow-rooted and will produce suckers if the roots are damaged[
]. This species suckers freely in the wild, forming quite large thickets[
Plants in this genus are notably susceptible to honey fungus[
Fruit - raw or cooked. A succulent flesh[
]. The ovoid fruit is usually yellow to greenish yellow, sometimes tinged with red, around 8 - 15mm long[
Seed - raw or cooked. Do not eat the seed if it is too bitter - see the notes above on toxicity.
Although no specific mention has been seen for this species, all members of the genus contain amygdalin and prunasin, substances which break down in water to form hydrocyanic acid (cyanide or prussic acid). In small amounts this exceedingly poisonous compound stimulates respiration, improves digestion and gives a sense of well-being[
The plant has potential use in erosion control[
The plant is considered to be an important habitat for Texas' native bees[
A green dye can be obtained from the leaves[
A dark grey to green dye can be obtained from the fruit[
Peachbush is a secondary genetic relative of the Japanese Plum (Prunus salicina ),and so it has the potential for use as a gene donor for crop improvement[
Seed - requires 2 - 3 months cold stratification and is best sown in a cold frame as soon as it is ripe[
]. Sow stored seed in a cold frame as early in the year as possible[
]. Protect the seed from mice etc. The seed can be rather slow, sometimes taking 18 months to germinate[
]. Prick out the seedlings into individual pots when they are large enough to handle. Grow them on in a greenhouse or cold frame for their first winter and plant them out in late spring or early summer of the following year.
Cuttings of half-ripe wood with a heel, mid summer in a frame[
Softwood cuttings from strongly growing plants in spring to early summer in a frame[
Layering in spring.
Division of suckers during the dormant season. They can be planted out direct into their permanent positions.