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Other Taxa & Unknowns "somalense nova" "Thai Socotranum" Sahel Group Lake Eyasi mystery som. - crisp. intergrade A. coetanum? The Sahel Group Adeniums in the Sahel west of Ethiopia are of unknown identity. There are a few herbarium specimens, but no live plants in cultivation that are available for study. In photos the plants look much like A. somalense , but the leaves and flowers look more like those of A. "obesum ". If anyone has more photos or live plants from the Sahel (any country east of Ethiopia), please contact me . Above: Plants of Adenium sp. near Tintane (west of Nema), in southeast Mauritania; bush grassland. Plants from this region have been described as A. honghel ; there are no specimens available for study. Photos: Helene Jousse (via Jan Schlogl) Above: Plants and flowers of Adenium sp. near Tintane (west of Nema), in southeast Mauritania; bush grassland. Plants from this region have been described as A. honghel ; there are no specimens available for study. Photos: Helene Jousse (via Jan Schlogl) Above: Two plants of an Adenium sp. near Bénoué National Park, northern Cameroon. Plants west of here have been described as A. honghel ; plants to the east have been described as A. speciosum . There are no specimens available for study. Photos: Joel Peterson Back to Top Adenium speciosum? Left two: Plant and flowers of an adenium near Kauda, South Kordofan, Sudan. It looks similar to A. somalense in Ethiopia and Kenya, but plants from this region have been described as Adenium speciosum . Click to enlarge. Photos: submitted by Ricardo Denis. Adenium honghel? Left two: Adeniums near Bakel, Senegal. Right two: Adenium near Kedougou, Senegal; this is a mesic habitat for adeniums. Plants from this region have been described as Adenium honghel . The flowers at first appear to have dark throats, but they actually have pink throats overlain with very thick nectar guides. Click to enlarge. Photos: submitted by Ricardo Denis. Right two: Adenium near Yankari, Alkaleri, NG-BA, Nigeria. Plants from this region have been described as Adenium honghel . This plants's flowers look much like those above from Senegal. Again, the dark-appearing throats are caused by thick nectar guides. Photos submitted by Ricardo Denis. Adenium "somalense nova" This taxon was discovered in the mid 1990s in Tanzania, and is in the trade as Adenium "somalense nova". The name is enclosed in double quotation marks to indicate that it is not validly published. In nature the caudex is globular and buried underground, with erect, barely succulent stems to about 4 feet (1.2 m) tall. In cultivation seedlings develop a short-conical caudex that is partially exposed. The plants grow fairly rapidly and make a large caudex compared to the size of the plant in a few years. The small flowers start appearing sparsely at the end of the growing season in fall, followed by a more profuse bloom through the winter while the plants are leafless. They are pink to red at the edges, fading to a white throat with prominent nectar guides. The anther appendages protrude slightly beyond the tube. Another population that looks very much like this taxon has been found more than 100 km away. Adenium "somalense nova" collected in Tanzania. The caudexes were underground. Photo: Andre Williams Six-year-old seedling of Adenium "somalense nova" in a 16-inch pot beginning to flower at the end of the growing season. Six-year-old seedling of Adenium "somalense nova" in a 16-inch pot flowering during winter dormancy. Left and Right: Flowers of Adenium "somalense nova" . This group of Adenium "somalense nova" were grown by Hiren Vaghela. This distinct strain has very narrow leaves. Click to enlarge. Photos: Hiren Vaghela. Adenium "somalense nova" in the Wild Above: Adenium "somalense nova" east of Usambara Mountains south of Same, Tanzania. Right: Same plant with caudex excavated. This is a small plant. Photos: Chuck Hanson Back to Top Adenium "Thai socotranum" Adenium "Thai socotranum", also called "Thai soco", are not related to A. socotranum. They are in fact dwarf forms of A. "arabicum" bred in Asia. They are extremely popular, and there are many named varieties. See more examples in the Thai socos section in the A. "arabicum" page "Thai Socotranum" Photo: John Franklin Roosevelt Back to Top A. "obesum" near Lake Eyasi, Tanzania Anomalous adenium plants near Lake Eyasi, Arusha, Tanzania. This is in the geographic range of A. "obesum ", but the plants are unusually caudiciform. More important, the flowers are atypical of either species, but closely match those of A. swazicum or boehmianum hundreds of miles to the south. There is a population of these anomalous white-flowered, dark-throated adeniums growing on a rocky granite hill above a hot spring. Photos: David Bygott. NOTE: There are surely many other anomalous adenium populations in the wild. If you know of any, please contribute photos and other information to further our knowledge of these plants. Back to Top Right: ...and a gigantic specimen in the same locality. Click to enlarge. Photo: Chris Schmeling via David Bygott A. somalense-crispum intergrade? Adenium near Bulo Burri (Bulobarde), Somalia, between the ranges of somalense and crispum. The leaves appear to be linear and crisped like crispum, but this is a tree like somalense. What is it? These two taxa hybridize readily in cultivation. Photo: John Lavranos. Adenium coetanum ? An Adenium in the Dirashe District of southwestern Ethiopia, near the borders with South Sudan and Kenya. The plant is the size of A. somalense , and it occurs within the range of that species. But the leaves look like those of "obesum ", which begins in southern Kenya. The flowers appear to have dark throats,which, if true, is not characteristic of East African adeniums. This plant is not far from an herbarium specimen labeled A. coetanum . This plant also resembles the old cultivar 'Singapore ', which has been sold as A. coetanum . DNA analysis indicates that 'Singapore ' is an intergrade between A. "obesum " and A. somalense (Dimmitt and Edwards 2021 ). Photos: (contributed by Ricardo Denis). Left: This photo was taken in Ethiopia, where adeniums "should be" A. somalense . But the foliage and flower look like those of A. "obesum ". Perhaps this is what has been described as A. coetanum . Photo: Jim & Roxie Esterle Back to Top Footnotes

Species The genus Adenium consists of 11 phenotypically recognizable types in cultivation. There are at least 8 good species in nature, and perhaps several more (see map below). For ease of labeling, this site treats each type as a separate species, and I will use the names that are popular among horticulturists until the taxonomic confusion has been sorted out. Specific epithets (the second word in a binomial [scientific] species name) that have not been validly published and incorrect published names are enclosed in double quotes. (Very important: single quotation marks identify a cultivar name.) The taxonomy page summarizes what is known about adenium species, and the nomenclatural issues page summarizes the problems. See Dimmitt and Edwards 2021 for a detailed analysis. Adenium oleifolium swazicum boehmianum Southern African Clade socotranum dhofarense "arabicum" Arabian Clade multiflorum somalense "obesum" crispum East African Clade Ambiguous Taxa "somalense nova" "Thai socotranum" Sahel Group Lake Eyasi mystery som. - crisp. intergrade Approximate known distributions of Adenium taxa. The map was drawn from a rough sketch by John Lavranos, based on about 120 European herbarium records and his extensive field observations. Anchor 1 * 2021. Dimmitt, Mark A. and Taylor Edwards. Adenium Taxonomy and Nomenclature : Progress Creates More Questions. Cactus and Succulent Journal (U.S.). Vol. 3 no. 4, pp 252-266. Available as a PDF on request to the first author. Footnotes

Gallery of Superior Cultivars Intraspecific Cultivars "arabicum" boehmianum crispum dhofarense multiflorum "obesum" oleifolium socotranum somalense swazicum Interspecific Hybrid Cultivars "obesum" x swazicum crispum x "obesum" "arabicum" x "obesum" "arabicum" x "obesum" x crispum Rare Crosses Double Flowered Cultivars

Hybrids containing Adenium somalense nova & crispum Waiting for contributions

Dimmitt Adeniums is the comprehensive website for genus Adenium. We cover: plants in the wild, cultivars, care, and much more all from the mind of the master gardner Mark A. Dimmitt. This website is dedicated to the genus Adenium , commonly called adeniums and desert roses. My main purpose is to showcase their diversity both in the wild and in cultivation. I also provide guidance to cultivating the plants in hot, arid climates, based on my 40+ years of experience. The content was compiled by Dr. Mark Dimmitt of Tucson Arizona, with images and information contributed by many plant explorers and growers all over the world (credited in the photo captions) . The site was designed by Brian Rasmussen . I intend this website to be a comprehensive source of knowledge about Adeniums. I welcome your comments, corrections, and especially additions of new photos and information beyond what is already here. 'Beautiful Mule' 'OMG!'

Hybrids containing Adenium somalense nova & swazicum Waiting for contributions

Adenium boehmianum Schinz Adenium boehmianum is closely related related to A . swazicum , and occurs on the other side of southern Africa in Namibia and southern Angola. It is an erect arborescent shrub, usually with barely succulent stems and only modestly swollen roots. In the northern end of its range it develops thick conical trunks. The leaves are the second largest in the genus. The flowers have broad petals that usually overlap, and are borne from late summer into early winter. This species shares a diagnostic trait with A. swazicum : petals are of uniform pink with no fading toward the dark throat, and very short anther appendages. A. boehmianum is uncommon in cultivation. A. boehmianum at the Huntington Botanical Gardens. The plant is about six feet tall. A. boehmianum flowers are usually circular in outline. Notice that the petal color does not fade toward the throat. Flowers and foliage of A. boehmianum . Flowers and foliage of A. boehmianum . Right: An example of pink flowers of A. boehmianum. Photo: Cheryl Acford Adenium boehmianum in the Wild Adenium boehmianum in Namibia. Photo: Dan Mahr Adenium boehmianum in Namibia. Photo: Dan Mahr Adenium boehmianum in Namibia. This one has a well developed conical trunk. Photo: Dan Mahr Adenium boehmianum in Namibia. Photo: Dan Mahr Adenium boehmianum in Namibia. Photo: Dan Mahr Adenium boehmianum in Namibia. Photo: Robert H. Webb Adenium boehmianum at Ojihipa, Namibia (Angolan border on the Kunene River). Photo: Ernst Van Jaarsveld. Flowers of Adenium boehmianum in Namibia on the Kunene River near Epupa Falls. Photo: Ernst Van Jaarsveld. Adenium boehmianum in northern Namibia, exhibiting a splendid succulent trunk. Photo: Ernst Van Jaarsveld. Adenium boehmianum near Okabadjia, Namibia. Photo: John Lavranos. Back to Top Footnotes

Adenium " arabicum" x crispum hybrids As far as I know, Miles Anderson of Miles’ to Go Nursery is the only person who has successfully made this F 1 cross. He got only five viable plants, but they were fertile. They have the large caudexes and sturdy, erect branches of “arabicum ”; the small plant size, foliage, and flowers were heavily do minated by the crispum parent. Third generation plants that I grew from these plants still showed the striped petals, and mostly quilled petals. Some of these are larger, up to five feet (1.5 m) tall. In my opinion the main value of this line is contributing smaller size and striped flowers into the “arabicum” x “obesum” x crispum line . These hybrids are apparently tetraploid, because they cross only with other 4n adeniums. Above left: The star-shaped flowers of some clones have flat petals, but most will quill in a couple of days (right). Left: One of Miles Anderson's original F1 plants of Adenium "arabicum" x crispum. The caudexes are very large compared to plant size. Photo: Miles Anderson. Miles Anderson's F2 crosses of Adenium "arabicum" x crispum also have relatively huge caudexes, but the flowers are still quilled. The promise of these plants is to get cripsum 's patterned flowers and smaller plant size into the tetraploid arabicum-"obesum " line. Plant at left is 5 years old in a 14-inch pot. Footnotes

Back to Gallery Cultivars of Rare Crosses or Unknown Parentage Here are a few oddballs that don't fit anywhere else. 'Beautiful Mule' 'Flame Tree' 'Bohemian Splash' 'Singapore' 'Candy Stripes' 'Crimson Picotee' 'Winter Remedy' 'Beautiful Mule' Parentage: Complex hybrid involving Adenium "obesum", swazicum, and crispum . ('Candy Stripes' x 'Black Raspberry') 'Candy Stripes' = A. crispum 'Famous Ancestor' x A. swazicum 'Perpetual Pink' 'Black Raspberry' = A. crispum 'Famous Ancestor' x A. "obesum " 'Black Ruby' Creator: Dimmitt 2003 Plant form: Naturally arborescent with thick trunk, major branches, and massive roots. Foliage resembles that of "obesum", except for more prominent white veins as in crispum. Deciduous. It can also branch basally and become a shrub. Flower: Round at first; with age the petals elongate and quill, becoming more star-shaped. Diameter at one week 84 mm, 35 mm petal width. Petals solid crimson-red outer halves, fading to pink at throat. Throat red with darker red strong nectar guides that extend onto the petals halfway to the tips. There are white calluses where each pair of petals fuse at the throat. (They turn red in older flowers.) Flowers continuously from mid spring through late autumn. Notes: I had high hopes for this cultivar when it was young. I love tree adeniums, and the flowers borne at eye level. Alas, it's completely sterile, hence the name. It seems to have no pollen, and it has never set a fruit. Worse still, although it roots easily from cuttings, it is exceptionally susceptible to root rot. I have lost many plants from watering once too late in the fall or too early in the spring. I don't sell it except to the most avid and diligent collectors. Above: The original seedling of adenium 'Beautiful Mule', 17 years old in an 18-inch pot. Far left: a new flower of adenium 'Beautiful Mule', showing excellent shape. Left: week-old flowers, showing how the petals elongate as the flower ages. The right photo shows more accurate color - crimson-red. Back to Menu Above: A grafted plant of adenium 'Bohemian Splash', about 7 years old. The original seedling is slow-growing. 'Bohemian Splash' (MAD639) Parentage: Complex hybrid involving Adenium boehmianum, "obesum", and crispum . A. boehmianum 'MAD193' x 'Happy Princess' Creator: Dimmitt 2010 Plant form: Vigorous (on grafts) upright shrub or tree with sturdy branches; tends to grow taller than wide. Deciduous. Flower: Round, 60 mm diameter x 26 mm petal width. Petals pink with many fine dark pink lines almost to the tips. Throat pinkish-red with prominent black nectar guides. Blooms prolifically from early summer to early winter. High flower count. Notes: This is my favorite boehmianum hybrid, because of its strong growth and profusion of colorful flowers. The great majority of boehmianum hybrids are weak and/or are very slow growing. They produce mostly inferior offspring in subsequent generations. Back to Menu Above: The flowers of adenium 'Bohemian Splash'. Left: A young grafted plant of adenium 'Bohemian Splash', about 2 years old. 'Candy Stripes' Parentage: Label lost; presumably Adenium crispum x swazicum . When this cross was made, the most likely parents were A. crispum 'Famous Ancestor' and A. swazicum 'Perpetual Pink' Creator: Dimmitt 2000 Plant form: Erect, arborescent, with large roots and thick main stems. Deciduous. Flower: Semi-star, 80 mm diameter x 27 mm petal width. Petals dark pink with 3 fine dark pink lines to the tips and numerous short streaks. Flowers age to light pink. Throat red with darker red nectar guides. Blooms prolifically during the warm months. Notes: The dark throat and short anther appendages indicate swazicum parentage (if it were boehmianum , it should contribute larger leaves); while the petal markings have to come from crispum. Neither species is known for having sturdy stems, so this erect plant is a treasure. This clone grows well from cuttings. I know of no other crispum-swazicum hybrids. Above: A new (left) and old flower of 'Candy Stripes'. Above: The original seedling of adenium 'Candy Stripes', 9 years old in a 24-inch box. Right: This hybrid of A. crispum x A. swazicum by JFR Exotics supports my conclusion about the parentage of 'Candy Stripes'. Photo: John Franklin Roosevelt. Back to Menu 'Crimson Picotee' Parentage: Primary hybrid between A. "obesum " and A. multiflorum . Creator: Dimmitt 1984 Plant form: Very large, erect shrub with thick, sturdy main branches and massive roots. Evergreen. Flower: Round-star, 70 mm diameter x 27 mm petal width. Petals white with broad bright red border. Throat white with few prominent nectar guides. Blooms sparsely but almost continuously year-round. Notes: I've made several "obesum"-multiflorum hybrids, but this was the only one worth keeping. The others were less vigorous, and flowered even more sparsely. Grows well from cuttings and makes a good grafting rootstock. Back to Menu Above: The original seedling of adenium 'Crimson Picotee', 10 feet tall in a 36-inch pot at 16 years old. Left two: the flowers of 'Crimson Picotee'. 'Flame Tree' Parentage: Complex hybrid of A. "obesum", swazicum, and somalense. ('Crimson Star' x A. somalense ) Creator: Dimmitt 1995 Plant form: Tree to at least 10 feet tall in 10 years, with thick cylindrical trunk. Roots not greatly swollen. Flower: Round/semi-star, 55 mm diameter x 20 mm petal width. Petals deep red, fading to near-white at the throat. Throat blackish-red with black nectar guides that extend halfway to petal tips as red lines. Notes: I have made only a few crosses with somalense, because I didn't have any good clones of the species until very recently. Such hybrids have little value as commercial pot plants because they get so big so fast. But they would make great landscape plants in tropical climates. I list this cultivar because I know of no similar hybrids. It also shows that somalense can contribute petal markings to hybrids. Do you have any somalense hybrids? Please contribute to our knowledge. Above left: The original seedling of adenium 'Flame Tree', 8 feet tall at 9 years old. Above right: The same plant at 17 years old, 10 feet tall in a 22-inch pot. Back to Menu Above: A 4-year-old cutting of adenium 'Singapore', already showing its conical caudex. 'Singapore' Parentage : Uncertain; possibly this is Adenium coetanum . See notes below. Origin: Introduced by the Singapore Botanical Garden in 1933. My plant is a cutting of Frank Horwood's clone from Abbey Garden. Plant form: Spreading shrub with conical caudex and swollen main stems. Evergreen. Flower: Very large, semi-star, 102 mm diameter x 30 mm petal width. Petals light pink with wide deep pink to light red margin. Throat white with few faint nectar guides. Blooms repeatedly during the warm months. Notes: This is the oldest named cultivar of adenium, dating to a time decades before adeniums became well known in horticulture. Albert Chan at the Singapore Botanic Garden showed the plant to the famous botanist Richard Eric Holttum. He identified the plant as A. coetanum , a taxon of questionable validity. There are a few herbarium specimens with this label that were collected from northern Uganda and Kenya south to northern Tanzania. Adeniums from this region are currently recognized as A. somalense in the north and A. "obesum " in the south. DNA analysis suggests that 'Singapore' is an obesum-somalense intergrade. Therefore it is probable, whatever its true identity is, that it originated in this region of East Africa. Frank Horwood succeeded in selfing his plant and obtained a handful of seedlings, which were fertile. All of the plants in the US labeled A. coetanum are probably descended from this one clone. Source: a 1980 letter from Frank Horwood . Above: The 4-inch flower of adenium 'Singapore'. Back to Menu Above: A 12-year-old cutting of adenium 'Singapore. 'Winter Remedy' Parentage: Adenium multiflorum x swazicum primary hybrid. (A. multiflorum 'MAD1' x A. swazicum 'Perpetual Pink' Creator: Dimmitt 1987. Plant form: Spreading shrub with massive roots. Semi-deciduous. Flower: Round/semi-star, 77 mm diameter x 27 mm petal width. Petals with wide medium pink margin, fading to near-white at throat. Throat red with no nectar guides. Flowers fade to light pink in a week. Inflorescence is indeterminate, produces buds and flowers for about 3 months. Winter blooming. Notes: This is one of a small number of winter-blooming adeniums. Above left: The flower of adenium 'Winter Remedy'. Above right: A 3-month old indeterminate inflorescense. The first flower was where my two fingers are gripping the peduncle. Back to Menu Above: The original seedling of adenium 'Winter Remedy' at 16 years old in a 24-inch pot. Cuttings grow the same massive roots in several years.

Adenium crispum x "obesum" hybrids This hybrid line was a huge breakthrough in adenium breeding. There were a few such crosses in the early 1990s in California and possibly elsewhere, but even though the F1 plants had the petal markings of crispum, the usually small, twisted flowers didn’t inspire much enthusiasm. In 1999 I sent a cutting of A. crispum to a collector in Taiwan (I later named it ‘Famous Ancestor’ . He propagated it and shared it with other growers. This species is difficult in hot, humid climates. The clone died out within a couple of years, but not before hybrids were made with A. “obesum”. First generation (F 1 ) hybrids inherit from "obesum" vigorous vegetative growth and large, colorful flowers. The crispum parent often contributes a substantial caudex, and quilled flowers with strong nectar guides that extend to the petal tips. Unfortunately, both parents tend to contribute weak stems. Plants of this line are usually slow-growing, taking at least 5 years to develop their character (in Arizona; they grow much faster in more tropical climates). After several generations the Taiwanese breeders had eliminated the quilled petals and created plants with large flat flowers exhibiting bold petal markings. The nectar guides on the petals often morph into bold blotches and stripes. All flowers with such petal markings are descended from A. crispum , and probably from 'Famous Ancestor'. By 2008 there were millions of plants and hundreds of stunning named cultivars all over Asia. The plants in this group are mostly small to medium-sized and slow-growing, with modest caudexes (about 2 feet [61 cm] tall and wide); but some are “obesum” -sized (3 to 4 feet [91-122 cm]). Only the best clones have sturdy stems; most need pruning every few years to maintain a neat form. Superior clones flower profusely throughout the warm season. Both parent species are very cold-sensitive, but many of the complex hybrids (second generation and beyond) are resilient as long as they’re kept dry during winter. Almost all cultivars on the market are grafted. See the superior cultivars page for a big gallery of these hybrids. Adenium ' Harry Potter ' was the first crispum-"obesum " hybrid with fairly flat petals and bold markings. The nectar guides have become blotchy stripes. It was created in Taiwan by C.F. Chang in 2003, only 4 years after the introduction of A. crispum . A first-day flower is at left; a week-old flower at right. A few more early crispum-"obesum " cultivars. Left: Adenium 'City' from Taiwan is an example of a flower with strong contrast between the background and the nectar guides. Below: New and older flowers of 'Star of Taiwan' Below: 'Classical' has bold blotches overlain by even bolder lines. Created by H.C. Chen. Footnotes