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Corynopuntia aggeria (Ralston & Hilsenbeck) P. Griffith 2002
Grusonia aggeria (Ralston & Hilsenbeck) E. F. Anderson 1999
Opuntia aggeria Ralston & Hilsenbeck 1989

I was not aware that Opuntia aggeria was a fairly recently described plant. Ralston and Hilsenbeck named it in 1989. Anderson came along and moved it from Opuntia to Grusonia in 1999 and P. Griffith moved it to Corynopuntia it in 2002. I have not heard any common names for it nor did I find any synonyms. I have not had my plants too long maybe six years so I am not sure how they will do in cultivation in the long run. So far they seem to be doing very good. 

Here is the description:
Plants, forming clumps to about 9 cm tall, roots tuberous, stems segments are short cylindrical to clavate, about 3.5 cm long to as much as 9 cm long and 1.5 to 3 cm in diameter, tubercles to 22 mm long mostly shorter to about 18 mm long. Glochids yellow, to about 3 mm long, spines mostly in distal areoles, 5 – 15 but sometimes only one, 3 – 5 cm long. Principal apical spines 0 – 5, ascending, diverging, reddish brown to gray, bulbous basally, round in cross section. Principal basal spines chalky white, bend downwards, flattened, twisted or curved. Flowers bright yellow and to 2.5 cm long. Habitat is South east Texas and into Mexico.

Above is the name of the genus that Anderson placed the plant in and that is Grusonia. So I looked in the Anderson book and he has the same term as in the description above; ‘distal areoles.’ So I looked in the NCL and it says the same thing. There is no photo of the plant in the Anderson book but there is in the NCL. That photo is useless for trying to see what the plant really looks like; much less seeing what distal areoles look like. That photo shows a plant in habitat and from over head with three flowers in bloom.
Fig. 1 shows the plant from the side, it is in a 15 cm pot and the plant is 24 cm in diameter. I have another that is not quite that wide. I have the plants in regular pots and not pans as they do have a tuberous root system. The deeper pots will allow the roots to grow to a better size. I do not know how large of a plant they become in habitat. Some of the plants in the genus can grow into a clump that can be several meters across. If C. aggeria remains as in individual plant of about 30 to 40 cm across or if the stems root down and make a train of plants I do not know. Neither the NCL nor Anderson mentioned the size of the plants. I went on the web and I also struck out in finding much useful information. Maybe it is because it is in the Opuntia group that no one pays much attention to the plant so there is little information out there.

Fig. 2 is the plant from more or less over head; I removed all the dead flower remains except one. Except for the spine shape the stems are much like those of C. bulbispina. Fig.  3 shows one of these distal areoles with spines growing out of it. A close look reveals the glochids sticking straight up from the top of the areole. Also almost invisible are a few long fine hair like spines that grow from the area of the glochids but hang down the stem to about the middle of the chalk white divergent spines. Growing below those are some other short spines; they grow more or less sideways. In the description above and in Anderson’s book there is no mention of radial or centrals spines. The NCL says there are from 1 – 15 spines and then says there are 1 – 3 central spines under 3 to 5 cm long. The way it is worded it sounds like there are 1 – 15 spines and also 1-3 centrals. Anderson says there are 1- 15 spines and he says that the principal spines number 0 – 5. To me those 0 – 5 principal spines are part of the 1 – 15 spines. I have to assume that the principal are all spines that are long and show up as light gray to chalky white. In that areole there are the three divergent spines.

Fig. 4 is another areole and from what I can see there are 7 of what I would call principal divergent spines. If comparing the spines on each areole it looks like each areole differs somewhat from the nearby areoles. This can be seen in photo 1. Each seems to grow the spine number, shape and how they stick out of the areole on their own. On many cactus plants each spine cluster will be exactly like the one next to it, above it, below it and on the whole plant. The spines grow out of a wooly pad on the areole and that wool seems to persist even at the lowest areoles on the stems. This can also be seen in photo 1.

Fig. 5 shows the leaves on the areoles on the flower buds. The stems also have leaves but they dry and fall out quite soon. In photo 6 the new stem growth to the right of the base of the flower tube has leaves on it. Just below the base of the flower tube can be seen a leaf that is all shriveled up and will soon fall out. The leaves start out being greenish red but soon turn brown and drop. In the description it says that the flowers are to 2.5 cm long. In Fig. 6 that is talking about the part from the flower down to where it grows out of the plant. In photo 5 are several flower buds that have flowers encased in their outer petals. It is from the bottom of the encased flowers that is measured. Every bud on this plant that I measured was 3.5 to 4 cm from plant to base of the flower. The thing I do not understand is why the diameter of the flower is not included in the description. I do not know many people that measure the length of the flower and never its diameter. To me the diameter is more important than the length.

Fig. 7 is of a flower and Fig. 8 is of 3 flowers even though there are 4 in the photo. I did not think to measure the flowers when open, and when I thought of it they all had faded. There is no indication that the plant will bloom again very soon. All the plants of this genus only bloom one time a year for me. Most of these flowers opened at about the same time. I am going to guess that the flowers when open wide were about 7 cm across. The filaments are quite large compared to a lot of flowers that size or even larger. They are cream color as is the pollen but both lean towards the very light yellow side. The style is the same color as the filaments but the stigma is a pale green. The center of the flower is darker and it looks as it is the green like the outer petals.

C. aggeria comes from Brewster County Texas and south to central Coahuila so it can take quite hot summers and temperatures down into the low 20s F. They grow fine in my regular soil mix and I give them a very bright place on my covered outside tables where they stay all year around.
I don’t know how many people have this plant but I have never seen it on a show table or on a sale table.