Begonia chlorosticta is a species from central Sarawak where is grows in lowland dipterocarp forest. It can be found on rocky slopes and damp cliffs at 450m elevation. Originally collected in 1967 and introduced into cultivation, it has since developed a reputation of being challenging to keep. I can attest to this, as I’ve lost count of how many times I’ve had to re-obtain it due to sudden melting episodes. It was given the designation U038 before being formally identified. For me it has been the most challenging Begonia species to grow, as it frequently goes through melting spells without any apparent change in environment or care. It can grow to over three feet tall, with cane- type growth. The intense variegation persists in adult plants, and only gets more dramatic as the plant grows. There are multiple forms of this species, usually identified as either green, red, or black. It can be difficult to distinguish between the types when plants are young. It has been suggested that Begonia sp. Kapuas Hulu is a form of chlorosticta, but, it is hard to say. The flowers are very similar.
It is from the section Petermannia which is distinctive in that species from this section tend to put out female flowers before males. This serves to prevent cross-pollination in the wild, but is also a bit of a bain for keepers of these species, as it often makes pollination impossible unless pollen is stored from a previous year, or another plant is also in bloom and can offer pollen.
The plant below is ‘red’ chlorosticta.
And here, the same plant a few months later with more mature foliage.
After being repotted into a taller bin,
I pollinated the ovary below with pollen from B.darthvaderiana, and surprisingly, within two days the tepals dropped. This is an almost sure sign of successful pollination. Not to say the seeds will be any good, but it’s the first step. Having had no success with creating darthvaderiana seed, despite many opportunities with many ovaries from many different plants, I was expecting pollination attempts even using this species as a father to be equally challenging. Next, the ovary will need to stay on long enough to dry properly, then it will need to be harvested at the proper time, then it will need to sit on a piece of paper for 2-7 days, and then it will need to be opened up and examined for fertility. If the seeds look good, they will be sorted by placing the seeds on a piece of paper, tilting at an angle, and collecting those which roll easily. Those that do, will be put through this process again, and those seeds will be the ones sowed.
About a year and a half after receiving this plant, it is beginning to actually grow. Sadly the ovary pollinated above did not produce viable seeds. They looked good under the loupe (40x) but did not germinate. Too bad! Chlorosticta can reach about 3′, but it rare to encounter such large specimens in cultivation, I’m not sure whether it is because it tends to melt back often, and for cultural reasons it does not reach it’s mature size, or because the high prices it’s now fetching prompt annual trimming. In any case, I moved mine to a taller bin recently and even though the substrate was left intact, just a quick lift into another bin, it lost a few leaves. Interestingly, some of the new leaves show no sign of red. The various ‘types’ of cholrosticta have always confused me. Depending on conditions the same plant can look bright red or pale green, and the black one is hardly black but just a darker red.