Miltonia spectabilis vs. Miltonia moreliana. Which is which?   Leave a comment

In a recent Facebook discussion, this flower was presented and the owner asked the audience to identify it.   The flower, a large purple Miltonia, could potentially be Miltonia spectabilis, Miltonia moreliana, or a hybrid containing genes from either of these two species.

A plant that I received as Miltonia moreliana, and very similar to the plant in question. Is it really moreliana?

A plant that I received as Miltonia moreliana, and very similar to the plant in question. Is it really moreliana?

Here is a link to Eric Lu’s Purple Miltonia

I thought that I would write a short discussion of these two species and talk about them in relation to this plant, so that I could keep from writing this over and over again, as is the nature of online discussions.

From the original description of Miltonia moreliana, in 1857.

From the original description of Miltonia moreliana, in 1857.

Miltonia spectabilis and Miltonia moreliana are both widely grown, widely used in hybridizing, and widely misunderstood and misidentified in collections.  The confusion occurs for several reasons: both are from Brazil, both are from the genus Miltonia and are very similar morphologically, and moreliana until recently was considered a variety of spectabilis.

Miltonia spectabilis, from Edward's Botanical Register (1815-1847)

Miltonia spectabilis, from Edward’s Botanical Register (1815-1847)

Miltonia spectabilis was described by Lindley in 1837, and used as the type for the entire genus (a “type” plant is typically the first one described of that genus, and used by taxonomists as a standard by which all other members of that genus are included).  But there is another population of plants, similar to spectabilis but significantly different enough to garner its own varietal name. (A variety of a species must be actually scientifically documented and published before it can be used, and then is referred to with the abbreviation var. If a form of a species has not been described as per these rules, it is referred to a “forma” which is abbreviated fma.) This population of plants was described in 1867 by Warner and given the name moreliana.  Interestingly, Warner himself considered this to be a separate species, although it was considered a variety by everyone else.

In 2002, another paper was published investigating these two flowers.  The paper, entitled A Morphometric Analysis of Floral Characters in Milt. spectabilis and Milt. spectabilis var. moreliana (Carlini-Garcia, van den Berg, & Martin), uses the measurements of the flowers and the flower parts to try and establish the final word on whether these two populations are varieties of each other or true species.  The paper is located on the web, at this link: spectabilis v. moreliana Paper.

Milt. moreliana 'Everglades'

Milt. moreliana ‘Everglades’

For those of you who don’t want to read it, I will provide a synopsis.  Multiple flowers from wild populations of these two flowers were collected and then measured in about as many different ways as one can measure.  The flowers themselves, and each individual part of the flower, were measured and the final measurements compared statistically between the two groups to determine if there actually was a discernible difference.  The upshot is that these two plants produce flowers that are indeed different enough to change Miltonia spectabilis var. moreliana into simply Miltonia moreliana, giving it the status of a full species.

So what are the differences between these two species?  How can the average grower determine what is growing in his greenhouse?

Miltonia spectabilis fma. alba, a tetraploid clone from Everglades Orchids.

Miltonia spectabilis fma. alba, a tetraploid clone from Everglades Orchids.

There are some differences between these two species that are not immediately apparent.  The ranges of each species are significantly different, with moreliana occurring north of the range of spectabilis, and possibly stretching all the way to Venezuela through the interior of Brazil.  Also, the times of peak blooming differ.  As I have observed, spectabilis always blooms earlier than moreliana, in the early summer or even late spring.  Milt. moreliana blooms later, in the late summer and early fall.  There is some overlap between these times, so it cannot be used to rule out one from the other.

But let’s look at the similarities.  The plants themselves are short, with a vigorous and rambling appearance thanks to the relatively long inter-nodal distance (the distance between bulbs).  Both of these species have small, flattened pseudobulbs, from which arise two sets of leaves with multiple enlarged bracts at the base of the bulbs.  The roots are thin and fine, as in all Miltonia species, an adaptation to their epiphytic habitat and a clue as to how to grow them (lots of water/humidity with excellent air-movement).  Both produce short inflorescense with a terminal presentation of the flowers.  Last, both species tend to present flowers sequentially, with only a single flower open at a time.  In some plants that I have seen, more than one flower may be technically open but this is a small period of overlap between the first flower dehiscing (falling off) and the second flower opening.  Milt. spectabilis may have two or more flower buds developing while the first flower is open, and moreliana tends to have only two flowers/buds total (again with only one open at a time).

Milt. moreliana 'Monarch'

Milt. moreliana ‘Monarch’

The size of the segments is distinctly different between the two species.  The most obvious difference is the size of the lip, with moreliana having a lip that is basically round, with a ratio between length and breadth that is about 1:1.  Milt. spectabilis’ lip is longer than wide, with a ratio of 1.5:1.  In general, the sepals and petals tend to be wider in moreliana, with a width of 1.5-2 cm, vs. 1-2 cm in spectabilis.  These characteristics give moreliana a stockier, broader appearance than spectabilis.  Also, spectabilis presents its flowers on a slightly longer peduncle (that part of the stem that includes both the stem and ovary) but again there is significant overlap.

Milt. Danny Denton 'Everglades', an advanced hybrid that looks almost identical to moreliana.

Milt. Danny Denton ‘Everglades’, an advanced hybrid that looks almost identical to moreliana.

All of this makes it seem as though identification of these two species can be confusing.  Statistically the measurements of flower parts of the entire species as a whole do not overlap, but between individuals this overlap can prove frustrating.  However, there is one specific difference between these two species that no one seems to talk about, despite the fact that it is the most obvious of all floral characteristics: color.  Yes, the difference between the two species can be narrowed down to a single dramatic difference.  Milt. moreliana is purple, and spectabilis isn’t.  Milt. spectabilis presents in three forms: white, white with a colored lip, or pale pink/rose.  But they are never purple.

I was confused about this, because I have never seen it recorded or written anywhere, scientific journal or otherwise.  My suspicions about this color difference have existed since I was shown my first true spectabilis, which was pink.  Next to it was a true moreliana, which was purple.  The difference in the sizes of the floral parts was quite distinct when the species were viewed side by side.  Since then, I have searched in vain for a white moreliana, and for a purple spectabilis.  I have not seen any.  But this kind of observation is completely subjective.  What if there actually was a purple spectabilis or a white moreliana, and I just hadn’t seen it yet?

My confusion became complete understanding when I re-read the van den Berg paper.  This time through, I read every word, including a small part that I had missed.  At the end of the paper, according to their final analysis, the authors have provided a key.  A key is essentially a step by step instruction on how to identify a plant sitting in front of you using whatever characteristics the author of the key feels is important, and identification keys are succinct and complete in the smallest detail.  At the end of each description of each species is the simple information about color that I missed the first time around.  “Petals and sepals white or light pink……..spectabilis” and “petals and sepals purple……..moreliana.”  I have yet to see any proof able to refute this idea.

Miltonia spectabilis fma. rosea, Everglades Orchids

Miltonia spectabilis fma. rosea, Everglades Orchids

I believe that the great majority of confusion about these two species has arisen in part due to the Happy Hybridizer, who assumes that since these two forms are the same species, and that interbreeding them and calling whatever results a Miltonia spectabilis is appropriate.  There is no name for the Milt. spectabilis x moreliana hybrid.   And despite the plethora of purple Miltonia hybrids that exist, not a single one lists Milt. moreliana as a parent.  What we now have is this frustrating population of plants that have been passed down from grower to grower, and used extensively in hybridizing, but are essentially misnamed and quite likely have genes from both of these species.

Milt. Woodlawn Ruby 'Woodlands', an advanced Miltonia hybrid with no mention of moreliana as an ancestor.

Milt. Woodlawn Ruby ‘Woodlands’, an advanced Miltonia hybrid with no mention of moreliana as an ancestor.

So, back to the plant at hand.  What is it?  I would like to be able to say that I know for certain.  I would like to be able to say it is moreliana.  There is some good evidence for this.  The flower’s measurements (ratios only, mind you) are within the range for moreliana.  The lip is a bit long, but again the ratios fall within those calculated from the measurements presented in the paper.  I think in the end the best that I can say about this flower is that to me, it looks like it could be moreliana.  And if it isn’t moreliana, then it is a hybrid.  Again, I have never seen a purple spectabilis, because there is no such thing.  And there you have it, I have answered the question completely and thoroughly, and still we don’t know what the answer is.  Welcom to the wonderful world of orchid taxonomy!


Posted September 7, 2015 by brianmonk in AOS Orchid Awards, Orchid Photography, Orchids

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