TRICHOCEREUS FLOWERING
FLOWERING OF ECHINOPSIS (TRICHOCEREUS) CACTI
The following describes the flowering of the San Pedro Cactus ( = Echinopsis pachanoi, Trichocereus pachanoi).
This description also applies to other Echinopsis (Trichocereus) species, such as:
1. Echinopsis peruviana (Trichocereus peruvianus, = Peruvian Torch Cactus).
2. Echinopsis lageniformis (Trichocereus bridgesii, = Achuma Cactus = Bolivian Torch).
1. Flowering of the San Pedro Cactus (Echinopsis pachanoi. Trichocereus pachanoi)
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1. Age of first flowering
The age at which a San Pedro Cactus first blooms varies.
The first flowering depends on the amount of light and nutrients a San Pedro Cactus receives.
Usually, a San Pedro Cactus blooms from about 30 to 40 centimetres in length.
If the San Pedro grows slowly, this is after about four years.
Buy flowering San Pedro Cacti here.
2. Formation of the San Pedro Cactus flower
The flowering of the San Pedro Cactus is the beginning of sexual reproduction.
Slightly below the growth point in the centre of the head of a San Pedro Cactus, dark brown wool first develops on several areoles.
areole = beige to brown felty spot from which thorns and flowers grow
The brown wool protects the beginning flower bud from pests, sun and cold.
These brown woolly hairs grow longer, and an oval bud with brown hairs slowly develops.
Such a dark brown tubercles grows into a brown hairy green flower bud about 20 centimetres long.
The long flower bud is perpendicular to the top of the stem.
Eventually the flower is mature, and will open by evening (Night bloomer).
3. Flowering period of the San Pedro Cactus
A San Pedro Cactus flowers when the Cactus is growing well, from March to September.
Sometimes a San Pedro Cactus plant blooms with more flowers at the same time (2 or 3 flowers).
Usually, several flower buds develop on a San Pedro Cactus, blooming a few days apart.
The flowering of a San Pedro Cactus occurs over several weeks in the summer period.
If a pollinated flower of a San Pedro Cactus produces seeds, the next flower blooms a little later.
4. Flowering times of the San Pedro Cactus
The San Pedro Cactus is a so-called ‘night bloomer’, flowering at night with large white flowers.
The opening of the flower of a San Pedro Cactus occurs in the late afternoon.
The large white flower is maximally opened around midnight.
Closing of the San Pedro flower begins early the next morning.
Halfway through the next day, the flower of the San Pedro Cactus is still slightly open.
Still later, the flower closes, becomes limp, droops down, and dries out.
5. Growth of the San Pedro Cactus flower
In the afternoon, the San Pedro Cactus flower opens as the inside of the flower grows.
In the morning, the San Pedro Cactus flower closes as the outside of the flower grows.
So a San Pedro Cactus flower grows during the time it blooms.
So at the end of flowering, the San Pedro Cactus flower is larger than at the beginning of flowering.
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PHOTOS OF FLOWERING OF THE SAN PEDRO CACTUS AND PERUVIAN TORCH CACTUS
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Below are pictures of the flowering of the San Pedro Cactus and Peruvian Torch Cactus.
The flower and fruit are covered with brown to black hairs, but sometimes also with white hairs !
The Cactus genus Trichocereus (now Echinopsis) derives its name from this.
tricho = hair.
cereus = columnar cactus.
Trichocereus = columnar cactus with hairs.
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 1. Thick green flower buds with brown hairs in the
top of the Peruvian Torch Cactus
(Echinopis peruvianana, Trichocereus peruvianus).
Note the longer spines of the Peruvian Torch Cactus
(photos 1, 2, 3) compared to the shorter spines of the
San Pedro Cactus (photo 4).
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 2. Opened white flower of the Peruvian Torch Cactus
(Echinopis peruviana, Trichocereus peruvianus).
The stamens are at the back of the flower, while the
pistil is in front.
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 3. Outgrown and wilted flower of the Peruvian
Torch Cactus (Echinopis peruviana, Trichocereus peruvianus).
Note the green, hairy, convex thickening at the base
of the flower.
This is the ovary in which the Cactus seeds
are formed.
This ovary forms after the flower has been pollinated
with pollen from another genetically different
(Echinopis) Cactus.
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 4. The green fruiting principle of the San Pedro Cactus
(Echinopis pachanoi, Trichocereus pachanoi) in detail.
. The fruiting principle has grown longer and also thicker.
The spent and wilted flower has contracted
and withered into a narrow dry brown stem.
Note the white hairs on the ovary and on the
flower tube (far right).
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Formation of seeds in the San Pedro Cactus (Seed formation)
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1. Fertilisation of the San Pedro Cactus
1.1 Pollination of the flower of the San Pedro Cactus
The yellow pollen of a San Pedro Cactus flower makes contact with the stigma of the pistil another San Pedro flower.
1.2 Fertilisation of the ova of the San Pedro Cactus
The sperm cells from the pollen grow into the stigma and down through the style of the pistil.
The sperm cells fertilise the ova in the ovary at the bottom of the flower.
The fertilised ova grow into black San Pedro Cactus seeds by cell division.
The San Pedro Cactus may also make seeds by pollination with its own pollen, but fewer seeds and also smaller seeds.
Fertilisation with another San Pedro Cactus that is genetically different, however, produces more seeds and larger seeds.
Genetically different = both San Pedro's are not cuttings from the same mother plant, or cuttings from each other.
2. Formation of Seed Berries in the San Pedro Cactus
2.1 Formation of San Pedro seed berries
After fertilisation, small black seeds grow in the base of the flower (ovary).
The flower tube and petals dry up and turn beige, drooping downwards.
At the end of the San Pedro Cactus seeds' growth period, the green seed berry cracks open lengthwise.
Inside the snow-white flesh lie hundreds of black San Pedro Cactus seeds.
2. Form of the seed berries of the San Pedro Cactus
The hairy seed berries are egg-shaped and green in colour.
On each seed berry are brown hairs and short green scales.
The length of a San Pedro seed berry (fruit) is about 30 mm.
3. Seeds of the San Pedro Cactus
The black seeds of the San Pedro Cactus (Echinopis peruviana, Trichocereus pachanoi) are 1 to 2 millimetres long and thick.
The length of the San Pedro Cactus seeds is slightly larger than the diameter.
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