Cattleya percivalliana albescens ‘Oro blanco’

[dodidoki]

Another caveat: if we follow the strict nomenclatura propagated by some eminent botanists within Paphiopedilum (Gruß, Braem), it can NEVER bloom completely alba - as this term in botany is exclusively reserved for plants that blooms without any colour pigmentation, i.e. with completely and all white flowers.
I guess a proper designation for David's and Istvan's flowers would be 'alboflava' (white and yellow). At least if you can't detect any pinkish blush, as mostly seems to be the case with Istvan's flower. Otherwise, probably, the correct designation might be 'alboflavescens' - or maybe 'flavoalbescens' would be even more appropriate as the yellow colour is certainly and fully present, while the slightly pinkish hue seems to affect only the white segments of David's flower (albecens means whittish/close to be(coming) white)!

Olaf mentioned those plants that can't produce anthocian, albino forms. I think that is the most appropriate terminology for these plants. Albino forms can be viride, viridoflava, alboflava, flava, alba etc.

 

[DrLeslieEe]

I know, Leslie...but I wonder, whether this holds true in a strict botanical sense? This would demand that these yellow-throated albino forms of the plant have been described and published validly as alba forms in accordance with the ICBN (International Code of Botanical Nomenclatura). Otherwise, I guess, we are dealing with what rightly might be considered a horticultural colourform?
Now there is a little digging for you to do!

"Always"? I wonder, whether the use of categorical statements in matters like these, always, is a wise thing?
What do you fx. think of this Catt. intermedia fma. alba 'Graue' SM/DOG - the photo of Hilmar Bauch's (Asendorfer Orchideenzucht) wonderful plant, that I hope he will forgive me borrowing for the sake of argument:
View attachment 43594

Even this flower will have yellow keels in back of lip.

 

[DrLeslieEe]

Copying from a 2014 Australian Orchid Review piece by Guido Braem (I am guessing the horse is too far out of the barn to pull it back in on this one).

albino: by botanical definition, a plant that lacks the possibility to produce anthocyanin pigments. It should be noted that plants have 3 groups of pigments, being

1. (a) anthocyanins, responsible for the red and brown shades,
2. (b) carotenes, responsible for the yellow colours, and
3. (c) chlorophylls, responsible for the “greens”.

Therefore, a plant correctly designated as an albino will not show any red or brown colour but can very well be green, yellow, white, or any combination thereof. As soon as any shade of red occurs anywhere in any part of the plant, the specimen is not an albino.

alba, album or albus (depending on the gender of the genus): a Latin word that simply means “white”. This term, as far as orchids are concerned, is used in connection with the colour of the flower. Only flowers that are pure white should be designated as alba/album. “Alba/album” plants are albinos, but we have already established that albinos are not necessarily “alba/album”

albinistic: a term that is used in various ways. The correct usage is for the designation of an albino or “alba/album”. This term can, therefore, be used for a yellow/green/white plant or an all-white plant. Unfortunately, the term “albinistic” is often erroneously used to designate a plant that is faintly but normally coloured.

A Cattleya that is white with yellow in the lip would seem to be an albino, but not an alba, according to Dr. Braem.

The definition of a white flower without any red anthocyanins can be designated as album, alba or albino based on the whims and fancy of the taxonomist of the day as well as the genera being described.

For example, the album godefroyaes and niveums still have yellow or green in their staminodes.

As for the designation albinistic, the flower must have some light or faint red anthocyanin somewhere on it.

 

[DrLeslieEe]

Olaf mentioned those plants that can't produce anthocian, albino forms. I think that is the most appropriate terminology for these plants. Albino forms can be viride, viridoflava, alboflava, flava, alba etc.

These terms are usually used by later and more learned taxonomists to clarify the type of white and yellow/green flowers.

 

[dodidoki]

These terms are usually used by later and more learned taxonomists to clarify the type of white and yellow/green flowers.

Just have a look at the humans. If there is no melanin production we call those individuals albino. We can call them alba but those humans are really not white, but pink. A real albino plant can produce chlorofill and xanthofill, too, both are physiological pigments that have important roles in the life of the plants ( not just in fotosynthesis but in production of hormones). I think this fact is that why taxonomist accept as albino forms all individuals, what have yellow colour on their flowers. On the other hand if we call a flower alba, it means white. That is the other reason why newly they are called alba just if the flower is white, other forms are called alboflava, albiviride, viride etc., depending on the color of the flower.

 

[terryros]

The definition of a white flower without any red anthocyanins can be designated as album, alba or albino based on the whims and fancy of the taxonomist of the day as well as the genera being described.

For example, the album godefroyaes and niveums still have yellow or green in their staminodes.

As for the designation albinistic, the flower must have some light or faint red anthocyanin somewhere on it.

In Braem's article, that focused on Paphs, he noted that a number of Paphs called album were not all white. I think he was admitting that the orchid world, not for the first time, had long ago deviated from strict botanical nomenclature. Throw in our tiffs about species, var., fma, etc and orchid naming has been and will continue to be a bit of a mess. Of course, humans are always a bit of a mess.