Sempervivum blooms come in a wide variety of shapes, sizes and colors. Often overlooked as the swan song of the rosette, I thought it might be nice to have a thread to celebrate their beauty and differences.
I will continue to edit this opening post to include new information as it pertains to the colors and shapes of blooms and their derivative species.
The bloom stalks can range from two and a half feet tall to just a centimeter above the rosette. Their shape, the shape of the flowers themselves as well as their color can be correlated with various contributing species of sempervivum. The following information will be a compilation of aspects gathered from members contributions. I'll start us off by listing some species I'm aware of and the distinctive characteristics of their subtypes:
Bloom stalks are often medium or small, under 10" tall, some varieties cascade while others stand more erect. Flowers from pure species range in color from reddish pink to white and tend to be monochromatic. Petals are soft and wider than other species.
Stalks are extra short, under 6", standing erect with very small numbers of flowers often less than 10. Flowers are pale yellow with brown dotted sepals. Petals are soft, small and thin.
Stalks are small to medium in size ranging from under 6" to over a foot depending on the size of the rosette and tend to stand upright. Pure flowers are a strong pink and closely spaced upon the stalk, slightly hybridized versions may have multi-tonal pink/mauve flowers.
Stalks tend to be small, under 7", and their flowers are more widely spaced often leading to smaller numbers per stalk. Larger stalks tend to branch out, but often there are so few branches that they appear to be very laterally oriented. Blooms are pale green with yellow/white overtones.
Bloom stalks are small but not necessarily short due to their strongly lateral formation. Fewer flowers and branches. Flowers are small with fewer stigmas/anthers per flower than other sempervivum. Petals are very distinct, glossy, yellow/white with a subtle green terminal stripe
None of my pure tectorums have bloomed, so I could use some help with the specifics on pure species to add to this list. What I can say is that tectorum bloomstalks tend to be large, 10" or more and contain larger numbers of flowers arranged conically. I believe them to have predominantly pink flowers of medium size with sepals often bearing the color of the rosette. Petals are soft with a satin texture.
I'm also less certain of this entry but from what I've observed these flowers tend to be bright pink on stalks that vary largely depending on the size of the blooming rosette. Upright branching on the smaller blooms while the larger ones tend to be conical. I was surprised to see that the cultivar 'Gold Marie' (which I'd thought to be nearly pure marmoreum) has white flowers with only a touch of pink. Some editing required here.
(photo by F. Wischka from sempervivum-liste.de)
Stalks tend to be medium or small under 10" and branch off at a near 45 degree angle. Flowers tend to be sparse and widely spaced. Particularly fragrant. The pure species have yellow flowers, but the hybrids I've seen have multi tonal pink/mauve blooms.
Bloom stalks are medium large, 12" or less with a slight cascade of looser hanging branches fanning outward. Blooms are white with pointed, soft petals that are exceptionally wide at the base.
Stalks are medium height 12" or less with branches directed at a sharp 45 degree angle from the stalk. They are sturdy and firm, as are their rounded petals which bear a slight gloss, overlap one another and are oriented in a closed tubular form. Tightly spaced flowers ranging in color from greenish white to bright yellow. Less anthers/stigmas than other sempervivum per flower.
Similar to the j. huefelii blooms, these have tightly spaced flowers with overlapping petals forming a closed, tubular bloom. Petals tend to be more sharply pointed than their heufelii cousin's and are white with a touch of green. Less anthers/stigmas than other sempervivum per flower.
(a photo Lynn posted of one of the selections)
Medium sized bloomstalks under 10" with loose branches of pale white flowers with subtle tan and pink overtones.
I'd love to add other species to this list, such as S. atlanticum, S. wulfenii and other's I am less familiar with. And please say something if I've misspoke on any points, I'm an enthusiast not a scientist and will most likely have missed a thing or two.
I'd also like to discuss the dominance in flower colors. So far I've gathered that the following is true:
Pink is dominant to all other colors, though the mixing may lead to deviations in hue or create a more multi tonal pink.
('Luftsprung', a grandiflorum cross involving a pink flowered cultivar)
Green is highly recessive, and will mimic the color of any flower it is crossed with.
White blooms with pink centers will lead to pink blooms even when crossed with yellow lowers (thanks Kevin). Pure white flowers may be co-dominant, changing the hue of the flowers they cross with drastically but ceasing to be pure white, I base this conclusion on the variations in monochromatic arachnoideum pink shades (some of which are extremely light) and the presence of white flowers with pink centers on some montanum and marmoreum hybrids.
Yellow is typically recessive but has the capacity to slightly alter the shade of flowers it's crossed with.
I will know much more about the dominance and blends of flower colors when all of my first year seedlings have bloomed, check back next summer for an update.
Ok enough of the science! if you have some nice bloom photos I'd love it if you could help us keep the thread alive by posting them here! Some of these blooms can really be beautiful, so show us your favorites.