''Cycnium tubulosum'', also known as the vlei ink-flower and the tissue paper flower, is a slender

hemiparasitic A parasitic plant is a plant that derives some or all of its nutritional requirements from another living plant. They make up about 1% of angiosperms and are found in almost every biome. All parasitic plants develop a specialized organ called the ...

perennial plant In horticulture, the term perennial (''wikt:per-#Prefix, per-'' + ''wikt:-ennial#Suffix, -ennial'', "through the year") is used to differentiate a plant from shorter-lived annual plant, annuals and biennial plant, biennials. It has thus been d ...

of the

broomrape ''Orobanche'', commonly known as broomrape, is a genus of almost 200 species of small parasitic herbaceous plants, mostly native to the temperate Northern Hemisphere. It is the type genus of the broomrape family Orobanchaceae. It is a weed on ...

family. Its range includes much of southern and eastern Africa, from

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

Ethiopia Ethiopia, officially the Federal Democratic Republic of Ethiopia, is a landlocked country located in the Horn of Africa region of East Africa. It shares borders with Eritrea to the north, Djibouti to the northeast, Somalia to the east, Ken ...

, including

Madagascar Madagascar, officially the Republic of Madagascar, is an island country that includes the island of Madagascar and numerous smaller peripheral islands. Lying off the southeastern coast of Africa, it is the world's List of islands by area, f ...

. It has creeping, straggling or upright stems, with few narrow, entire leaves and erect, white or pinkish, slightly

zygomorph Petals are modified leaves that form an inner whorl surrounding the reproductive parts of flowers. They are often brightly coloured or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''coroll ...

flowers on a long tube, with five lobes, reminiscent of a ''

Phlox ''Phlox'' (; "flame"; plural "phlox" or "phloxes", ) is a genus of 68 species of perennial and annual plants in the family Polemoniaceae. They are found mostly in North America (one in Siberia) in diverse habitats from alpine tundra to open ...

''-flower. It may not always be fully dependent on the supply of minerals by other plants, but usually makes connections with the roots of grasses. It can be found in moist, short grasslands, reaching altitudes of about . Its conservation status in South-Africa is "least concern".

Description

The vlei ink-flower is a

hairless Hairless, also known as H, is a well-characterized Drosophila gene. Since Hairless is a dominant loss of function mutation, many mutations to Hairless are embryonic lethal, but there are several viable hairless mutants. This specific Drosophila ...

or nearly hairless, hemiparasitic, high perennial

herbaceous plant Herbaceous plants are vascular plants that have no persistent woody stems above ground. This broad category of plants includes many perennials, and nearly all annuals and biennials. Definitions of "herb" and "herbaceous" The fourth edition o ...

, with angular stems having four flat sides, which are creeping, straggling or upright, that may have side branches or not, and sometimes there are a few glandular hairs. These stems carry few distanced leaves arranged oppositely or nearly so, which are approximately

linear In mathematics, the term ''linear'' is used in two distinct senses for two different properties: * linearity of a '' function'' (or '' mapping''); * linearity of a '' polynomial''. An example of a linear function is the function defined by f(x) ...

, widest at midlength, with a pointed cartilaginous tip, with a very short leaf stalk or seated, glossy, the margin entire or with a few teeth, rather thick, the veins sunken, long and wide. Its flowers are long, reminiscent of a ''Phlox''. These are set individually in the axil of a bract on a slender but rigid

pedicel Pedicle or pedicel may refer to: Human anatomy *Pedicle of vertebral arch, the segment between the transverse process and the vertebral body, and is often used as a radiographic marker and entry point in vertebroplasty and kyphoplasty procedures ...

of long, which does not carry any bracts subtending the flower. The five

sepal A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106 Etymology The term ''sepalum'' ...

s are fused into a high bell- to cone-shaped calyx tube, with ten veins, and ending in five almost lanceolate keeled lobes, that become narrower towards their tips and are long. The corolla is white, pinkish or purple and consists of five

petal Petals are modified leaves that form an inner whorl surrounding the reproductive parts of flowers. They are often brightly coloured or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''corol ...

s, which are fused into a curved, cylindrical long

corolla tube Petals are modified leaves that form an inner whorl surrounding the reproductive parts of flowers. They are often brightly coloured or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''coroll ...

. Above the "limb", the corolla becomes an approximately flat disk in diameter, that splits into five ovate lobes with a rounded margin, with the two lobes at the outside of the curve merged over a greater length than the others. Inside the corolla tube are five

stamen The stamen (: stamina or stamens) is a part consisting of the male reproductive organs of a flower. Collectively, the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filament ...

s with softly hairy filaments topped by long hairless, oblong anthers. The style does not reach the stamens, and is topped by a thickened, pointy stigma. The fruit is a hairless, short, oblique, slightly compressed, oval capsule of long and wide, topped by a short and obliquely beak, and has

coriaceous This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Glossary ...

valves. The plant discolors to black when drying.

Taxonomy

The plant was first described by

Carl Linnaeus the Younger Carl Linnaeus the Younger, Carolus Linnaeus the Younger, Carl von Linné den yngre ( Swedish; abbreviated Carl von Linné d. y.), or ''Linnaeus filius'' (Latin for ''Linnaeus the son''; abbreviated L.fil. (outdated) or L.f. (modern) as a botani ...

in 1782 as ''Gerardia tubulosa''. Other species that initially were in this genus have later been assigned to ''

Stenandrium ''Stenandrium '' is a genus of flowering plants in the family Acanthaceae native to the Americas, with 50 species of perennial herbs ranging from the southern United States to northern Argentina and central Chile. Species 50 species are accepted ...

'' (

Acanthaceae Acanthaceae () is a Family (biology), family (the acanthus family) of dicotyledonous flowering plants containing almost 250 genera and about 2500 species. Most are Tropics, tropical Herbaceous plant, herbs, shrubs, or twining vines; some are epip ...

), ''

Agalinis ''Agalinis'' (false foxglove) is a genus of about 70 species in North, Central, and South America that until recently was aligned with members of the family Scrophulariaceae. As a result of numerous molecular phylogenetic studies based on vari ...

'' (

Scrophulariaceae The Scrophulariaceae are a family of flowering plants, commonly known as the figwort family. The plants are annual and perennial herbs, as well as shrubs. Flowers have bilateral (zygomorphic) or rarely radial (actinomorphic) symmetry. The Scr ...

), and '' Micrargeria'' (

Orobanchaceae Orobanchaceae, the broomrapes, is a family (biology), family of mostly parasitic plants of the order (biology), order Lamiales, with about 90 genus, genera and more than 2000 species. Many of these genera (e.g., ''Pedicularis'', ''Rhinanthus'', ...

). In 1835,

George Bentham George Bentham (22 September 1800 – 10 September 1884) was an English botanist, described by the weed botanist Duane Isely as "the premier systematic botanist of the nineteenth century". Born into a distinguished family, he initially studie ...

though the species should be in the genus '' Rhamphicarpa'', and made the

new combination In Taxonomy (biology), biological taxonomy, a combinatio nova (abbreviated comb. nov. or n. comb.) refers to the formal renaming of an organism's scientific name when it is transferred to a different genus, reclassified within a different specie ...

''R. tubulosa''. In his book ''Die Pflanzenwelt Ost-Afrikas und der Nachbargebiete'' of 1895,

Adolf Engler Heinrich Gustav Adolf Engler (25 March 1844 – 10 October 1930) was a German botanist. He is notable for his work on plant taxonomy and phytogeography, such as ''Die natürlichen Pflanzenfamilien'' (''The Natural Plant Families''), edited with K ...

assigned the species to Bentham's genus ''Cycnium''.

Phylogeny

Recent DNA-analysis has revealed the evolutionary relationships between many of the species in the broomrape family. ''Cycnium tubulosum'' is most related to '' C. adonense'', and more distantly to '' C. racemosum''. The genus '' Cycnium'' is

monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

and the

sister group In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

of a

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

consisting of the genera '' Buchnera'' and ''

Striga ''Striga'', commonly known as witchweed, is a genus of parasitic plants that occur naturally in parts of Africa, Asia, and Australia. It is currently classified in the family Orobanchaceae, although older classifications place it in the Scrophul ...

''. Most related to the clade consisting of ''Cycnium'', ''Bruchnera'' and ''Striga'' is a clade consisting of '' Xylocalyx'' and '' Graderia''. The current insights in these relationships are expressed in the following tree.

Distribution and habitat

The vlei ink-flower is known from Angola, Botswana, Eswatini, Ethiopia, Kenya, Madagascar, Malawi, Mozambique, Namibia, Nigeria, Rwanda, Somalia, South Africa, South Sudan, Tanzania, Uganda, Zaire, Zambia, and Zimbabwe. It can be found in moist, short grasslands, reaching altitudes of about .

Ecology

The vlei ink-flower has white or rosy-tinged (sometimes purple) flowers that open in the evening, and have long narrow corolla tubes. These traits all occur in flowers that are pollinated by

hawkmoth The Sphingidae are a family of moths commonly called sphinx moths, also colloquially known as hawk moths, with many of their caterpillars known as hornworms. It includes about 1,450 species. It is best represented in the tropics, but species ar ...

s, although a clear scent was not observed. ''

Hippotion celerio ''Hippotion celerio'', the vine hawk-moth or silver-striped hawk-moth, is a moth of the family Sphingidae. It was described by Carl Linnaeus in his 1758 Lepidoptera in the 10th edition of Systema Naturae, 10th edition of ''Systema Naturae''. Dis ...

'' and '' Nephele comma'' have been seen to visit ''C. tubulosum''.

References

{{Taxonbar, from=Q15314325 Orobanchaceae Plants described in 1782 Flora of Africa