This thread is meant to illustrate the different stages a Cattleya seedling passes through on its way from seedling to adult plant. The photos here are all of Cattleya rex seedlings deflasked in March 2014.
When the seedlings are first deflasked, they do not look like Cattleyas at all. They do not have pseudobulbs, and they grow in a monopodial (upright) habit, like a Phalaenopsis.
This tiny seedling looks nothing like an adult Cattleya! Its leafspan measures about 1.5 centimeters. (2014)
These mounted seedlings are no more than 1-2 cm in leafspan. They show the monopodial growing habit characteristic of very young plants. (2014)
Look like Phalaenopsis? Nope, these are still Cattleyas! They have grown to a size of about 10 cm from leaf tip to leaf tip. (2016)
At a certain point, the seedling will stop growing vertically and transition to the sympodial growth habit that we see in adult Cattleya plants. A small growth will form off to the side of the main plant and the new leaves will start looking more like those of an adult. (2016)
These first couple of transitional leaves will have something of a pseudobulb but they still don't look quite like an adult Cattleya. (2016)
Finally, after one or two transitional-looking leaves, the plant will put out its first true adult pseudobulb. It will look like a miniature version of an adult cattleya. This seedling's first true pseudobulb and leaf measure about 10 cm tall. (2017)
From this point, the plant will grow larger with every new leaf until it reaches adult size.
This seedling is on its third adult leaf which measures about 18 cm. (2017)
After several years of adding larger and larger growths, this plant will be large enough to bloom. It will put out a sheath in the new growth, buds will appear within a month, and the plant blooms just as the new bulb is completed. (2019)
And then it's time to celebrate! (August 2019)