Orbea (genus)

Orbea
Orbea variegata
Systematics
Order : Enzianartige (Gentianales) Family : Dog poison family (Apocynaceae) Subfamily : Silk plants (Asclepiadoideae) Tribe : Ceropegieae Sub tribus : Stapeliinae Genre : Orbea
Scientific name
Orbea
Haw.

Orbea is a genus of plants from the subfamily of the silk plants (Asclepiadoideae). The main distribution area is in southern Africa . Individual species are also native to other parts of Africa and the Arabian Peninsula .

description

Habit of Orbea variegata

Illustration of Orbea lutea subsp. vaga

Vegetative characteristics

The genus Orbea includes thornless, stem-succulent species, some of which are also rhizome-forming , whose highly branched shoots form compact to diffuse clumps that can be up to 3 m in diameter. In most species, the diameter of the lumps is on the order of 5 to 30 cm. The height of the lumps is about 5 to 15 cm. The roots are fibrous. The firm, fleshy shoots are prostrate, sometimes with upright shoot tips, or the shoots stand upright. They reach a length of 1 to 25 cm. The diameter (without the warts) is usually around 10 mm, in some species even larger, with only one species only 5 mm and less. The basic color green or gray-green, rarely brownish surface is bare with purple-brown spots. The warts are conical and protruding, often laterally flattened and concentrated in four, longitudinal rib-like zones, less often only loosely in four rows, or irregularly arranged in four to five rows along the shoot. Each wart has a soft, more or less long / short pointed leaf rudiment at the tip, rarely the tip is also hardened. The leaflets are decrepit and often reduced to scales. The stipules are in pairs, are ovate to rounded and glandular. The milky sap is clear, colorless or, in one species, yellowish.

Large flower of Orbea ciliata

Small flowers of Orbea decaisneana

Inflorescences and flowers

One to three, rarely up to five, inflorescences per shoot are formed, which can arise at almost any height on the shoot. Depending on the type of flower, each inflorescence can have up to 40 flowers, which open gradually or in rapid succession, rarely at the same time. The short, bald inflorescence stem with a length of up to 15 mm has lateral appendages and can have one to several, lanceolate, decrepit bracts .

The flowers give off a carrion odor, or smells of excrement. They usually contain nectar . The hermaphrodite flowers are radially symmetrical and five-fold. The five sepals are lanceolate and long, pointed.

The five petals are wheel-shaped to bell-shaped, rarely fused double bell-shaped. Depending on the species, the crown has a diameter of 1 cm to 10 cm and is often heavily thickened below the base of the corolla lobes and forms a pronounced, so-called annulus (or ring) around the corolla tube; occasionally this is also funnel-shaped. There are often purple stripes on their bare and smooth exterior. Their wrinkled to almost smooth inside is rarely covered with blunt, multicellular papillae , more often with single-celled papillae and the wrinkles are arranged in a reticulate pattern. The crown is whitish, cream-colored, yellow, (light) -green, red or brown, and monochrome or often with reddish or purple-colored stripes, bands or spots. The corolla tube is mostly flat-cup-shaped or almost absent; occasionally formed almost exclusively by the annulus. The approximately triangular, lanceolate or egg-shaped, pointed tips of the petals are flat, spread out or bent back, or with bent edges. They are basal or between a quarter and half of the total length. The edges of the tips are often covered with vibrating, club-shaped cilia .

The corolla usually consists of two rows of bare, rarely papillate-downy lobes, some of which are fused and not clearly separated from one another, or which are partly reduced to the interstaminal series. The secondary crown can be yellowish, brownish or purple-red in color, depending on the species. The secondary crown usually sits on a pentagonal stalk up to 3 mm. The five outer interstaminal corolla lobes are more or less almost square, with entire margins, bidentate or in two parts, splayed and flat to upright, sometimes also deeply cup-shaped or urn-shaped. There may be an upright corner near the base that encloses a small pit of nectar. The inner staminal corolla lobes are pressed against the back of the anthers , are often higher than these and about as high as the stylus head. At the base they are flattened dorsoventrally , at the top end with pedicels and with lateral fin-like appendages on the back. The approximately rectangular to hemispherical anthers lie horizontally on the top of the stylus head. The margins often do not shrink back and can cover the pollinia . The guide rails running more or less upright are not embedded in the gynostegium tissue. The pollinium is D-shaped, the transparent edge is turned from the outer corner to the back surface. The more or less winged caudiculae (or translator arms) are broadly attached to the rhombus-shaped corpusculum .

Fruits and seeds

The follicles are usually paired at an angle of 30 to 40 ° to each other and are oriented upwards or horizontally. Depending on the species with a length between 4 and 18 cm and a diameter of 4 to 10 mm, the spindle-shaped, stem-round follicles have a blunt or pointed, but not beak-like, upper end. Its smooth, bare surface shows interrupted, longitudinal purple, thin stripes. The egg-shaped seeds with a length of 5 to 9 mm and a width of 3.5 to 6 mm have lateral 0.7 to 0.8 mm wide "wings" and are brown-yellow, medium-brown or light brown in color. The pure white head of hair is 15 to 25 mm long.

Chromosome number

The number of chromosomes in Orbea miscella and Orbea verrucosa is 2n = 22 or in Orbea paradoxa and Orbea melanantha 2n = 44.

differences

In Peter Bruyns' cladistic analysis, the genus Orbea is defined by a single synapomorphism :

• the crest of the point of attachment of the Pollinia are turned to the dorsal surface.

However, this characteristic has only been proven in the species that could be examined for this characteristic. But there are several vegetative features that are characteristic of the genus Orbea :

• the generally clear and brightly spotted shoots,
• the smooth outer surface of the shoots
• the warts, which narrow from the base and taper into a slender “tooth” without differentiating into a leaf rudiment
• often non-glandular stipules appear at the base of this leaf equivalent

Some characteristics are also found in the closely related genera Duvalia and Huernia , but these differ in the formation of the secondary crown . In Orbea the inner and outer circle of the secondary corolla is not clearly separated on the staminal column, as is the case with Duvalia and Huernia . The Pollinaria are different; in Orbea the corpusculum is longer and the pollinia are D-shaped. In Orbea, the guide rails are not embedded in the tissue of the ancillary crown, as can be observed in the two genera mentioned.

Occurrence

The species of the genus Orbea are widespread in South Africa , Botswana , Namibia and Zimbabwe, as well as in the adjacent parts of southern Angola , southern Zambia and southern and central Mozambique . Smaller occurrences isolated from this main distribution can be found in southern Zambia, Malawi and northern Mozambique, in Tanzania , Kenya , Uganda , Somalia , Ethiopia , Eritrea , in western Sudan , southern Algeria and in Niger , in southern Mali and in northern Burkina Faso , as well as another occurrence in the South Atlantic in southern Mauritania and northern Senegal . On the Arabian Peninsula , this genus has been found in Saudi Arabia , Yemen and Oman . However, many areas in which Orbea species have suitable habitats are still very little botanically researched, so that further evidence can be expected.

Systematics

The genus Orbea was established by Adrian Hardy Haworth in 1812 . Type species is Orbea variegata . The genus Orbea belongs to the Subtribus Stapeliinae from the tribe Ceropegieae in the subfamily Asclepiadoideae within the family Apocynaceae .

After the revision of the Monograph of Orbea and Ballyanthus (Apocynaceae - Asclepiadoideae - Ceropegieae) in 2002 on a cladistic basis by the South African botanist Peter Vincent Bruyns (* 1957), the species of the formerly independent genera Orbeanthus , Orbeopsis , Pachycymbium and Angolluma were included in the now much larger genus Orbea s. l. included. For the species Orbea prognatha , the new monotypical genus Ballyanthus was established , but it is not generally recognized. In addition, the synonymization of Orbeanthus is not widely accepted. Since this revision, a new species of the genus ( Orbea elegans ) has been described.

Orbea halipedicola

Orbea maculata

Orbea namaquensis

Orbea pulchella

Orbea schweinfurthii

Orbea semota var. Lutea

Orbea variegata

Orbea wissmannii

The genus Orbea s. l. now about 56–60 species:

• Orbea abayensis (MGGilbert) Bruyns : It occurs in southern Ethiopia.
• Orbea albocastanea (Marloth) Bruyns : It occurs in southern Namibia.
• Orbea araysiana (Lavranos & Bilaidi) Bruyns : It occurs in southern Yemen.
• Orbea baldratii (ACWhite & B.Sloane) Bruyns : With two subspecies:
  • Orbea baldratii (ACWhite & B.Sloane) Bruyns subsp. baldratii : It occurs in western Eritrea.
  • Orbea baldratii subsp. somalensis Bruyns : It occurs in northern Somalia.
• Orbea carnosa (Stent) Bruyns : With the subspecies:
  • Orbea carnosa (stent) Bruyns subsp. carnosa : It occurs in South Africa.
  • Orbea carnosa subsp. keithii (RADyer) Bruyns : It occurs from Zimbabwe to KwaZulu-Natal.
• Orbea caudata (NEBrown) Bruyns : With the subspecies:
  • Orbea caudata subsp. caudata : It occurs from western Tanzania to southern tropical Africa.
  • Orbea caudata subsp. rhodesiaca (LCLeach) Bruyns : It occurs from Zimbabwe to northern Botswana.
• Orbea chrysostephana (Deflers) Bruyns : It occurs in Yemen.
• Orbea ciliata (Thunb.) LCLeach : It occurs in the Capensis.
• Orbea circes (MGGilbert) Bruyns : It occurs in southern Ethiopia.
• Orbea conjuncta (ACWhite & B.Sloane) Bruyns : It occurs in Limpopo .
• Orbea cooperi (NEBrown) LCLeach : It occurs in South Africa.
• Orbea cucullata (Plowes) Meve : It occurs in Yemen.
• Orbea decaisneana (Lem.) Bruyns : It occurs in Sudan and from Algeria to Senegal and Niger.
• Orbea deflersiana (Lavranos) Bruyns : It occurs on the southwestern Arabian Peninsula.
• Orbea denboefii (Lavranos) Bruyns : It occurs from Kenya to northern Tanzania.
• Orbea distincta (EABruce) Bruyns : It occurs from southeastern Kenya to northeastern Tanzania.
• Orbea dummeri (NEBr.) Bruyns : It occurs from eastern tropical Africa to Zaire.
• Orbea elegans Plowes : It occurs in northern South Africa.
• Orbea fenestrata (Plowes) Meve : It occurs in Yemen.
• Orbea gemugofana (MGGilbert) Bruyns : It occurs from southern Ethiopia to Uganda.
• Orbea gerstneri (Letty) Bruyns : It occurs in South Africa. With the subspecies:
  • Orbea gerstneri (Letty) Bruyns subsp. gerstneri :
  • Orbea gerstneri subsp. elongata (RADyer) Bruyns
• Orbea gilbertii (Plowes) Bruyns : It occurs in northern Ethiopia.
• Orbea halipedicola L.C.Leach : It occurs in Mozambique.
• Orbea huernioides (PROBally) Bruyns : It occurs in northern Somalia.
• Orbea huillensis (Hiern) Bruyns : With the subspecies:
  • Orbea huillensis (Hiern) Bruyns subsp. huillensis : It occurs from southern tropical Africa to northeastern Namibia.
  • Orbea huillensis subsp. flava Bruyns : It occurs in northern Namibia.
• Orbea knobelii (Phillips) Bruyns : It occurs from Botswana to the Free State .
• Orbea laikipiensis (MGGilbert) Bruyns : It occurs in northern Kenya.
• Orbea laticorona (MGGilbert) Bruyns : It occurs from Sudan to Ethiopia.
• Orbea longidens (NEBrown) LCLeach : It occurs from southern Mozambique to northeastern KwaZulu-Natal.
• Orbea lugardii (NEBrown) Bruyns : It occurs in southern Africa.
• Orbea luntii (NEBrown) Bruyns : It occurs in southwestern Oman.
• Orbea lutea (NEBr.) Bruyns : With the two subspecies:
  • Orbea lutea (NEBr.) Bruyns subsp. lutea : It occurs from Zimbabwe to Free State .
  • Orbea lutea subsp. vaga (NEBr.) Bruyns : It occurs from Angola to South Africa.
• Orbea macloughlinii (Verdoorn) LCLeach : It occurs from the Capensis to KwaZulu-Natal.
• Orbea maculata (NEBrown) LCLeach : With the subspecies:
  • Orbea maculata (NEBrown) LCLeach subsp. maculata : It occurs from southwestern Zimbabwe to KwaZulu-Natal.
  • Orbea maculata subsp. kaokoensis Bruyns : It occurs in northwestern Namibia.
  • Orbea maculata subsp. rangeana (Dinter & A.Berger) Bruyns : It occurs in western and southern Namibia.
• Orbea melanantha (Schlechter) Bruyns : It occurs from Mozambique to South Africa.
• Orbea miscella (NEBrown) Meve : It occurs in the Capensis.
• Orbea namaquensis (NEBrown) LCLeach : It occurs in South Africa.
• Orbea nardii Raffaelli, Mosti & Tardelli : It occurs in Oman.
• Orbea paradoxa (I.Verd.) LCLeach : It occurs from South Africa to southern Mozambique.
• Orbea parviloba (Bruyns) Meve (Syn .: Orbea wissmannii var. Parviloba Bruyns ): It occurs in Yemen.
• Orbea pulchella (Masson) LCLeach : It occurs in the Capensis.
• Orbea rogersii (L.Bolus) Bruyns : It occurs from southeastern Zimbabwe to KwaZulu-Natal.
• Orbea sacculata (NEBrown) Bruyns : It occurs from Ethiopia to northern Somalia.
• Orbea schweinfurthii (A.Berger) Bruyns : It occurs from Uganda to Botswana.
• Orbea semitubiflora (LENewton) Bruyns : It occurs in northern Tanzania.
• Orbea semota (NEBr.) LCLeach : It occurs from Rwanda to eastern tropical Africa. With the two subspecies:
  • Orbea semota subsp. orientalis Bruyns
  • Orbea semota (NEBr.) LCLeach subsp. semota
• Orbea sprengeri (Schweinfurth) Bruyns : With the two subspecies:
  • Orbea sprengeri (Schweinfurth) Bruyns subsp. sprengeri : It occurs from north-eastern Sudan to Kenya.
  • Orbea sprengeri subsp. commutata (A.Berger) Bruyns : It occurs on the southwestern Arabian Peninsula.
  • Orbea sprengeri subsp. foetida (MGGilbert) Bruyns : It occurs in Ethiopia.
  • Orbea sprengeri subsp. ogadensis (MGGilbert) Bruyns : It occurs from eastern Ethiopia to northern Somalia.
• Orbea subterranea (EABruce & PROBally) Bruyns : It occurs from southern Ethiopia to northern Tanzania.
• Orbea taitica Bruyns : It occurs in Kenya.
• Orbea tapscottii (Verdoorn) LCLeach : It occurs from Botswana to South Africa.
• Orbea tubiformis (EABruce & PROBally) Bruyns : It occurs from southern Somalia to Kenya.
• Orbea ubomboensis (Verdoorn) Bruyns : It occurs from eastern Zimbabwe to KwaZulu-Natal.
• Orbea umbracula (MDHenderson) LCLeach : It occurs from southeastern Zimbabwe to Mozambique.
• Orbea valida (NEBrown) Bruyns : With the subspecies:
  • Orbea valida (NEBrown) Bruyns subsp. valida : It occurs from southern Zambia to northern Botswana and northeastern Namibia.
  • Orbea valida subsp. occidentalis Bruyns : It occurs from southern Botswana to Namibia.
• Orbea variegata (L.) Haw. : It occurs in South Africa.
• Orbea verrucosa (Masson) LCLeach : It occurs in South Africa.
• Orbea vibratilis (EABruce & PROBally) Bruyns : It occurs from southern Ethiopia to northern Tanzania.
• Orbea wilsonii (PROBally) Bruyns : It occurs from Uganda to northern Kenya.
• Orbea wissmannii (O.Schwartz) Bruyns : It occurs on the southwestern Arabian Peninsula. With the varieties:
  • Orbea wissmannii (O.Schwartz) Bruyns var. Wissmannii
  • Orbea wissmannii var. Eremastrum (O.Schwartz) Bruyns
• Orbea woodii (NEBrown) LCLeach : It occurs in KwaZulu-Natal.

No longer counted in this genus:

• Orbea prognatha (PROBally) LCLeach => Ballyanthus prognathus (PROBally) Bruyns

Use as an ornamental plant

In areas without frost, some Orbea species and varieties are used as ornamental plants in sunny locations , especially in semi-arid and arid areas they can be kept in gardens. In areas with frost, they must be overwintered in the greenhouse or rooms or are cared for in the greenhouse all year round or used as indoor plants . However, basically only one species ( Orbea variegata ) is widely used as a houseplant. Orbea variegata is considered to be relatively easy to care for. They produce numerous flowers, which, however, smell bad. Other species are only available from specialist nurseries. Cultivation has meanwhile also led to numerous culture hybrids.

swell

Individual evidence

1. ↑ Synopsis plantarum succulentarum cum descriptionibus synonymis locis, observationibus anglicanis culturaque . R. Taylor, London 1812, (online) .
2. ↑ ^{a b} Birgit Müller, Janine Kiel, Focke Albers, Ulrich Meve: Orbea . In: Focke Albers, Ulrich Meve (Hrsg.): Succulents Lexicon Volume 3 Asclepiadaceae (silk plants). Pp. 189-190.
3. ↑ ^{a b} D. HC Plowes: Orbea elegans Plowes sp. nov .: an attractive new stapeliad from northern South Africa (Apocynaceae - Asclepiadoideae - Ceropegieae). In: Asklepios. 90, 2004, pp. 14-17.
4. ↑ ^{a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am an ao ap aq ar as at au av aw ax ay az ba bb bc bd be bf bg bh bi bj bk bl bm bn bo bp bq br} Rafaël Govaerts (Ed.): Orbea - World Checklist of Selected Plant Families des Royal Botanic Gardens, Kew. Last accessed on November 13, 2018.
5. ↑ Gordon Cheers (Ed.): Botanica: The ABC of plants. 10,000 species in text and images . Könemann Verlagsgesellschaft, 2003, ISBN 3-8331-1600-5 , p. 619 .
6. ↑ Orbea variagata on Cactus-art.biz

literature

• Birgit Müller, Janine Kiel, Focke Albers, Ulrich Meve: Orbea . In: Focke Albers, Ulli Meve (Hrsg.): Succulents Lexicon Volume 3 Asclepiadaceae (silk plants). Ulmer, Stuttgart 2002, ISBN 978-3-8001-3982-8 , pp. 189-208.
• Peter V. Bruyns: Monograph of Orbea and Ballyanthus (Apocynaceae - Asclepiadoideae - Ceropegieae). In: Systematic Botany Monographs. 63, 2002, American Society of Plant Taxonomists, Ann Arbor, ISBN 0-912861-63-0 , pp. 1-196.

On-line

• Sigrid Liede-Schumann, Ulrich Meve: The Genera of Asclepiadoideae, Secamonoideae and Periplocoideae (Apocynaceae) - Orbea Haw. (Ceropegieae - Stapeliinae). (accessed on May 11, 2011)

Web links

Commons : Orbea  - album with pictures, videos and audio files

• Gerald S. Barad: Pollination of Stapeliads. (here also a simple schematic drawing of a pollinarium with pollinium, caudiculae (translator arms) and corpusculum) (accessed on May 11, 2011)