Buddleja globosa and Buddleja araucana (nappii)

Revised June 2014


B. globosa gets very large and is covered in little orange ball shaped flowers in May or June.

Buddleja globosa

Buddleja (Buddleia) globosa is found in Chile and the most westerly part of Argentina. It is a very large shrub with large green leaves and intriguing golf-ball flowers about 15mm in diameter, arranged in spikes of five to nine flower balls each with twenty-five or more little individual flowers. It is probably the most popular garden Buddleja after B. davidii and was the first Buddleja to be introduced to Europe in the 18th century. It is fully hardy, undemanding and evergreen although it can grow too large for many gardens: it can easily reach 5 metres in height and width. Depending on cultivar and position it can flower May to July and the bees love it. Seed pods form during the summer months ripening in September (in the UK), which later split when dry to release the tiny wingless seeds. But seed will only set on certain individuals.

This is because most Buddlejas from the Americas are dioecious: that is they have separate male and female plants. There is some confusion about B. globosa because the flowers often appear to have both male (stamens) and female (pistil) parts but one or the other is non-functional. This is called cryptic dioecy and species that display this are described as being cryptically dioecious, although in older texts it can be described as micro-dioecious. Hermaphroditic plants of this species may also exist (trioecious). More on sexing these Buddleja can be found below.


Most B. globosa plants have bright orange flowers.

There are several cultivars: Cally Orange; Lemon Ball; RCB RA-C-11; and HCM98017 to name a few. The differences can be very subtle. Cally Orange is supposedly a brighter orange; Lemon Ball is a shade lighter but not exactly the colour of a lemon and is female; RCB RA-C-11 is a wild collected specimen with a longer and earlier flowering period from April through to June. RCB RA-C-11 (from Cotswold Garden Flowers) appears to be male cultivar, although it is possible that it may be hermaphrodite. There was also a variegated form, which I have never seen; I have been told both that it had leaves spotted in yellow much like the hybrid B.x weyeriana 'Flight's Fancy' and also that it had delineated yellow margins. Unfortunately the plant is now lost and I cannot confirm which type of variegation it displayed.


The orange B. globosa in the photos is female
and regularly sets fertile seed, producing these large seed heads.


B. globosa HCM98017 has very pale yellow flowers.

B. globosa HCM98017 is really different and has very pale cream-yellow flowers and smaller leaves. Unfortunately the flowers aren't really bright and don't show up well against the foliage. HCM98017 has not yet set seed and close examination of the flowers leads me to believe that it is a male plant.


B. globosa HCM98017 (left) has very pale yellow flowers when compared to the species.


The bees aren't fussy - any B. globosa will do.


B. araucana has slightly deeper orange flowers and narrower leaves than B. globosa.

Buddleja araucana

Buddleja araucana (formerly called B. nappii) is a very similar species that may flower a little earlier in a May during a normal year. It seems most of the specimens in the UK are derived from a shrub at Kew Gardens in London and I believe it to be male. B. globosa comes from the Andes whilst B. araucana is more easterly, found mostly in Patagonia (Argentina). Although the two species are hard to distinguish the ranges of the two species do not overlap and there is not any evidence for intermediate types between the two species. The diagnostic feature, at least according to David Stuart who wrote the RHS Plant Guide on Buddleja, is the brown tomentum on the underside of the leaves, stems and flower buds of B. araucana. The leaves are also narrower and less bullate (that is a less crinkled top surface) than B. globosa. In the wild B. araucana is something of a xerophyte living in dry regions where the differences must be accentuated; it seems to be the soft life in England that makes it appear much more like B. globosa.


The buds of B. globosa (left) are different to those of B. araucana (right).
Note the different shape and brown fuzz on B. araucana.

Hybrids

There are hybrids of both B. globosa and B. araucana. The Buddleja x weyeriana hybrids are F2 plants of B. globosa x B. davidii, i.e.: (B. globosa x B. davidii) x (B. globosa x B. davidii). Salmon Spheres is a cross of B. globosa and B. crispa, whereas Winter Sun is a cross of B. araucana and B. officinalis. These latter two hybrids are similar with felted leaves and pink-flushed flowers that fade to yellow, Winter Sun having much larger leaves and growing bigger. B. globosa is also known to hybridise with a number of other species from both Asia and Africa.


The flowers of B. globosa (left) are also slightly different to those of B. araucana (right).


B. globosa female (top left), the male HCM98017 (top right),
un-named B. globosa male, (bottom left) and male B. araucana (bottom right).

A supersize version is available here

Determining the Gender of Buddleja globosa or araucana

As mentioned above both these species are dioecious and it is often hard to determine the sex of a plant. In some species it can require specific staining of the anthers or ovaries and microscopic examination to look for viable pollen or ovules to determine whether a plant is male (described as staminate), or female (pistilate). However, with Buddleja it may be possible for the gardener to work out the sex of a plant. I have observed that the males are flowering up to two weeks before the female, although I am working with a small sample of one. Possibly this has evolved to ensure that the pollen is available to the females immediately upon opening. Assuming the reasonable proximity (within a bee's range) of a suitable source of pollen female plants will set seed. Identifying a male plant may be possible using only a hand lens.

In the photos (left) the female flower does not appear to have stamens, although these are present: they are withered and brown with no apparent pollen being shed, somewhat hidden by the corolla tube hairs. HCM98017 has pale yellow bi-lobed stamens much the same colour as the corolla and with visible pollen. The un-named male plant conveniently has bright white stamens that are much more visible. The cultivated B. araucana is also male but the stamens are orange and difficult to see, not only due to the colour being the same as the corolla but also because the corolla tube has more hairs within. All have a similar shiny green stigma that is redundant in the males.

These features should be easier to see on the Supersized Image.


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