OrchidSafari
Orchids whose names begin with W, X, Y or Z - Xylobium, Zootrophion and Zygopetalum
Moderator:Marilyn Light
September 11, 2002

Copyright Marilyn H. S. Light 2002

[Pre-chat Handout]

At the end of the alphabet, we find a melange of interesting, odd-looking and fabulous blooms represented by Xylobium, Zootrophion and Zygopetalum respectively. Just because their names begin with letters at the end of the alphabet does not mean that they should be ignored and thankfully, they are not.

Xylobium, a Central to South American genus of some 20 species, is not often seen in collections. Xylobiums grow intermediate to warm under Cattleya conditions. Higher altitude species do best when given a rest after making up their annual pseudobulb. The plants are tufted epiphytes well suited to pot culture. Flowers range from cream to peachy pink, sometimes with markings on the petals and sepals. The lip can be cream to reddish purple. The most showy species have multi-flowered inflorescences that arise from the base of the pseudobulbs. Xyl. foveatum may be found growing at higher altitudes in Costa Rica, Nicaragua, Panama, Ecuador, or Peru. It bears upright spikes of up to 20 cream to yellow flowers in spring. Xyl. variegatum of Costa Rica and Ecuador is similar but with a red-blotched orange lip. It grows at 800 to 100 meters elevation. The semi-pendulous inflorescences of highly variable Xyl. leontoglossum are produced in October/November in Ecuador and Peru at up to 2000 meter elevation. Flowers are light orange with a cherry blotch on the lip and variable blotching on the floral segments. All species are worthy of a place in a collection. Keep your eye open for artificially propagated plants.

Zootrophion is a genus of pleurothallids once included with the Masdevallias. It is obvious from the unusually shaped flowers and the plant form that these are very different to what we now know as Masdevallias. Luer published the generic name Zootrophion in 1982. Flowers of the dozen or so species resemble a menagerie of bird heads, each flower is closed excepting the side slits that resemble the eyes of some menacing bird hence the generic name. A collection of species can be as interesting in terms of names and colors as in flower form. Zootrophion dayanum has typically dark wine-red flowers with glaring eyes. The compact plant produces flowers once or twice a year. Even though these orchids grow at higher altitudes in South America, they adapt wonderfully to intermediate conditions. The plants are quite drought-tolerant but to have handsome specimens it is best to keep them watered year round.

Zygopetalum is a South American genus of about 15 species. The handsome, robust plants grow either as terrestrials or epiphytes They can grow quickly so overpotting is not as risky as with some orchids. Species are characterized by having large showy fragrant flowers with large blue, mauve to reddish striped or solid-colored lips. Zygo. maxillare has a solid bluish purple lip, a characteristic that has been passed on the progeny. Zygo. mackayi, sometimes confused with Zygo. intermedium, is one of the largest with plants producing up to two 3-foot spikes of 7 to 10 flowers per pseudobulb. The flowers smell of hyacinth. Zygopetalum has been hybridized with range of closely related genera including Promenea but it is the multi-generic hybrids with up to six composite genera which are the most intriguing. It was George Black who started much of the exploratory breeding with this group. In 1967, he registered two pivotal hybrids, Otonsia (Otostylis x Aganisia) Broadway and Bateostylis (Batemannia x Otostylis) Silver Star, from which Hamelwellsara June and other intergenerics have emerged. Hamelwellsara June shows the influence of both Zygo. crinitum and maxillare but we also see the addition of Aganisia cyanea in the green flowers that are heavily blotched and lined wine red. In an experimental cross of Bollea violacea and Zygopetalum B. G. White, an unknown originator showed just what the hybridizer genie can produce. Bollopetalum Midnight Blue is almost solid colored deep wine to blue with a white picotee lip. Propetalum Mathina produces up to 3-inch wide yellow flowers with mahogany stippling . Given that it is a primary cross of miniature Prom. xanthina and massive Zygo. mackayi, we should be impressed. This primary hybrid is fertile and has given rise to many interesting hybrid progeny.

Zygopetalums are interesting as species and as interspecific hybrids. Just a few species have been combined to produce some lovely hybrids including green flowers with white lips. Other species, uncommon in cultivation, await their turn at the hybridizers hand. Zygo. brachypetalum has solid-colored petals and sepals unlike the blotched nature of many of the others but the segments are reflexed in the specimens seen. This could prove to be dominant trait in progeny which would be unfortunate. Zygo. mosenianum has an almost entirely white lip with a delicate waterfall of amethyst stippling. It would be interesting to explore this characteristic as is seen with Miltoniopsis. In Zygo. Artur Elle, we see three species (Zygo. crinitum, mackayi and intermedium) come together to produce a magnificent solid-colored bloom.

Zygopetalums and their intergeneric hybrids all like having adequate water year round and especially during growth spurts. They perform well in a variety of mixes. It is best to use the root character as a guide for choice of medium and pot size. Vigorous thick roots can manage a more open mix and a more generous pot while finer-rooted or less vigorously rooted plants might do better with a finer, more water-retentive mix. Generally, plant growth is not a challenge but getting certain hybrids to bloom is. Try varying reducing the day length to around 12 hours while ensuring that there is a good differential between day and night temperatures.

 [Discussion begins]

MarilyninOttawa
Zootrophion dayanum
Are the eyes not menacing! These Zootrophions are interesting to grow and quite easy too! They flower once or twice a year. Zootrophion dayanum has typically dark wine-red flowers with glaring eyes. The compact plant produces flowers once or twice a year. Even though these orchids grow at higher altitudes in South America, they adapt wonderfully to intermediate conditions. The plants are quite drought-tolerant but to have handsome specimens it is best to keep them watered year round.

N_Calif_Kathy
I always liked those, but thought there was a yellow one (in J&Ls list)

pecteilis_in_KY
I read that zootrophions need a rest. Aren't most of them vines? How would you rest them?

MarilyninOttawa
Zootrophion hirtzii has yellow flowers with reddish markings. Some species are more beige but most have red to maroon flowers. They are not really vines but produce aerial keikis and so they can seem over extended. They do not seem to rest but I have not grown all the species.

The flowers vary in size from species to species but are generally 1/2 to 1 inch in length. Some kinds have flattened flowers while others have more inflated blooms. The eyes can be large as in dayanum or quite narrow. You must cut the flower open to do pollinations.

Orchidglade
Where does one get a bee-sized knife?

MarilyninOttawa
I did cross-pollinate two Zoo. atropurpureum. I used a a new razor blade to slice the front off the flower. The flower substance is crisp and so this process is easily accomplished. Then you do your toothpick act and later on collect seed.

N_Calif_Kathy
So many Australians grow and hybridize with Zygopetalums that I thought they were from Australia.

Orchidglade
I remember Monkhouse saying in Vancouver that they had already gotten 50 genera Zygo hybrids and were shooting for 100!

John_in_Arcadia_CA
Marilyn - Have you ever heard of a Zygo species called latens.

MarilyninOttawa
No, I have not, there does not seem to be a Zygo latens listed as a valid species. There are no specific epithets at all like that name

art,simpsonville_sc
ARE ZYGOS CONSIDERED COOL GROWERS? Just wondered . All the buds blasted on mine this summer.

MarilyninOttawa
Zygos bloom in winter for me so I have not had your problem. With the heat we had this summer, I might worry but many orchids including Disa flowered right through the 80's and 90s. Flower bud blasting is a different problem than a plant preference for cool temps. The Zygo mackayii I have grew and flowered consistently in Barbados. I suspect that blasting could come from insufficient water. These plants like lots of water!

John_in_Arcadia_CA
All of the Zygo pictures are most interesting!!!!

MarilyninOttawa
Thank you for the comments about the pictures. The one limitation on presentations by genus is access to good photos and personal experience with a particular genus. We now have an extensive slide library which helps a lot.

N_Calif_Kathy
There is a nice form of Hamelwellsara June called 'Indigo', which is very grape purple.

Orchidglade
As I remember, H. June has the fragrance of PEPPER.

MarilyninOttawa
Is Zygo. Artur Elle not lovely? I asked some hybridizers for comments on breeding outcomes (there has been one cross offered by Ross Tucker of NZ) but had no responses.

N_Calif_Kathy
There have been several Promenea crosses that are spectacular also, but my ability to contact John (woolfe?) from Australia went no where.

MarilyninOttawa
When I first encountered the Zygo integenerics, I wondered what the hybridizing goal was. Some of the grape-colored clones are so dark they are almost lost in a dimly lit room. I suspect that increased flower number was one goal. Improved flower shape, another. Certainly, a range of color and marking is possible, and now with Promenea introduced, we are seeing more yellows.

Orchidglade
I bought a multigeneric Zygo hybrid at Home Depot that blooms every 2 months and seems to enjoy our warm weather down here. I would suppose one breeding objective is to get the Zygos heat tolerant. And they seem to have had success with that.

N_Calif_Kathy
I thought it was to introduce other colors other than mackayi's. Like crinitums'

art,simpsonville_sc
When does Promenaea xanthina bloom? I got mine in bloom and haven't seen a bloom since. Mine has grown quite a bit but I haven't seen any flowers.

N_Calif_Kathy
Well I was going to put in a request for Promenea to be a Marilyn topic for the future... I think there's wonderful potontial for these Zygo intergenerics. To a degree they all have the same shape, but the variation in color is great. I think the turn around time (flask to bloom) is reasonable too. Adelaide is selling in the US, you can search for them online, and JEM has some interesting hybrids..

MarilyninOttawa
I purchased all my Sarcochilus from Florafest. Good material. I have been doing some hybridization between Promenea and Lycaste. Not yet bloomed but these are much more compact growers than the Zygos. When you grow under lights, you must have compact plants.

Orchidglade
John Woolff of Florafest gave a talk on Zygo hybrids here a couple of years ago. They have great potential as heat tolerant Department Store pot plants

MarilyninOttawa
I have several Promeneas including xanthina, stapeliodes, guttata, ovatiloba and several Meadow Gold. I have several hybrids in the pipeline. Promeneas are in bloom year round and xanthina blooms twice yearly for me. It may depend on the plant you have as to blooming frequency but they generally flower when they produce new growths. Prom. xanthina blooms earlier than the others.

Promenea xanthina and other species are fragrant. Zygos are fragrant also. Their flowers are long-lasting and the plants resist pests in general. I really do not believe that heat is a problem with Zygos. They simply like to have access to lots of water so you have to keep them damp, breezy and growing under bright conditions. Many Zygos grow more or less in the open in the wild.

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