Gorteria diffusa

Gorteria diffusa
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Clade:	Asterids
Order:	Asterales
Family:	Asteraceae
Genus:	Gorteria
Species:	G. diffusa
Binomial name
	Gorteria diffusa; Thunb. 1798
Synonyms
	Gazania diffusa; Chrysostemma calendula, Gorteria calendula, G. diffusa subsp. calendula; G. affinis, G. diffusa subsp. intermedia;

Last updated September 28, 2023

Gorteria diffusa is a highly variable, small annual herbaceous plant or rarely a shrublet that is assigned to the daisy family (Compositae or Asteraceae). Like in almost all Asteraceae, the individual flowers are 5-merous, small and clustered in typical heads, and are surrounded by an involucre, consisting of in this case several whorls of bracts, which are merged at their base. In G. diffusa, the centre of the head is taken by relatively few male and bisexual yellow to orange disc florets, and is surrounded by one complete whorl of 5–14 infertile cream to dark orange ray florets, sometimes with a few ray florets nearer to the centre. None, some or all of them may have darker spots at their base. The fruits remain attached to their common base when ripe, and it is the entire head that breaks free from the plant. One or few seeds germinate inside the flower head which can be found at the foot of plants during their first year. The species flowers between August and October.^[1] It is called beetle daisy in English and katoog (cat eye) in Afrikaans.^[2]^[3] It can be found in Namibia and South Africa.

Description

Gorteria diffusa is initially erect, but quickly develops into a creeping annual of 2–20 cm (0.79–7.87 in) high that may sometimes survive and change into a shrublet. It is very variable in the number, shape, color and spots of the ray florets, and fourteen discrete forms have been distinguished. Its stems are branching at the base and often also more towards the end of the stems. They are reddish or green in color, and are set with long stiff hairs. The leaves near the base are 2½–9 cm (1–3½ in) long and 2–10 mm (0.079–0.394 in) wide. The leaves on the stems become gradually smaller further toward the tip, and may be ½–5 cm (0.2–2 in) long and 1–10 mm (0.04-0.4 in) wide. They are widest below midlength, mostly entire, but sometimes pinnately incised, with many stiff hairs on the upper surface, and the margins curled downward.^[1]

The flower heads are at least 2 cm (0.8 in), but mostly 3–5½ cm (1.2–2.2 in) across. The eighteen to thirty-two green or reddish bracts have red or blackish tips and together compose a pitcher-shaped involucre, which later becomes more inflated and woody. The free tips of the involucral bracts cover at least the upper two-third, are initially more or less upright but bend out later. This involucre encloses one complete, and sometimes a second incomplete whorl of somewhat overlapping infertile ray florets, in some forms seven to nine, in other forms twelve to fourteen, which may range in base color from almost white, through yellow to orange, with the underside ranging from grayish to dark orange-brown. These may have a darker zone at the base that may be clear yellow or orange-brown. There may also be yellow marking on all ray florets or dark blotches on some or all of them. Ray florets with blotches may be relatively small and brighter colored compared to those without or have the same size and color. These egg-shaped, oval or narrowly oval ray florets reach at least as far out as or more often much further than the involucral bracts, are 10–23 mm (0.39–0.91 in) long and 2–6 mm (0.079–0.236 in) wide, have an pointy or blunt tip with mostly four teeth. The dark blotches are raised or flat, dark green, brown or purple with black, with one to four small white spots, with stripes and sometimes hairy away from the base. Within the whorls of ray florets are thirty to forty yellow or orange disc florets, each star-like with five lobes, the outer circle bisexual, those at the center functionally male. The disc florets have hairs on the outside, sometimes more near the top and few or many very short glandular hairs. The style has two branches, less so in the male florets in the center of the disc.^[1]

The one-seeded, indehiscent fruits (called cypselas) are about 4 mm (0.16 in) long and have an asymmetrical pear shape, flatter facing the center of the flower head, the surface hairless near its foot, but felty hairy near its tip, and without ribs, sometimes with globe-shaped glands and twisted twin hairs. The pappus is absent or consists of a minute fringe.^[1]

Differences with other Gorteria species

Forms of G. diffusa with thirteen ray florets per head (which always have dark spots) differ from G. corymbosa , G. personata , G. parviligulata (all with eight ray florets per head), and G. piloselloides (with either five or eight ray florets), and differ from G. alienata , G. integrifolia and G. warmbadica (all without spots). The form of G. diffusa with eight florets per head (which is consistently found only in the Richtersveld, and has 18–31 narrowly triangular involucral bracts) differs from G. alienata, G. integrifolia and G. warmbadica (all with thirteen ray florets), from G. parviligulata and G. personata (ray florets not reaching beyond the tips of the involucral bracts), from G. corymbosa (has bristle-like involucral bracts), and G. piloselloides (has five ray florets with 15–20 involucral bracts, or eight ray florets with 35–45 bracts).^[1]

Taxonomy

Gorteria diffusa was described in 1798 by Carl Peter Thunberg, a Swedish naturalist who is sometimes referred to as "the father of South African botany". German botanist Kurt Polycarp Joachim Sprengel reassigned the species in 1826, creating the new combination Gazania diffusa. The famous Swiss botanist Augustin Pyramus de Candolle described in 1838 Gorteria affinis, which was in 1865 demoted by William Henry Harvey to Gorteria diffusa var. intermedia. De Candolle in 1838 also described Gorteria calendulacea, which was demoted by H. Roessler in 1959 to a variety of G. diffusa, to be raised to subspecies by him in 1973. Ernst Heinrich Friedrich Meyer described Chrysostemma calendulacea in 1838 in the same book as De Candole. A DNA comparison executed by Frida Stångberg and Arne Anderberg showed that populations from the south that had previously been included in G. diffusa belong to the same taxon as Gorteria personata subsp. gracilis, and have been assigned by them to Gorteria piloseloides, an existing available synonym. They also concluded that G. diffusa subsp. parviligulata represents a species somewhat distanced from the typical G. diffusa, and assigned it to the new combination Gorteria parviligulata. Finally they established that two different groups of G. diffusa subsp. calendulacea clustered with more typical G. diffusa from central and northern areas respectively, and confirm these forms should be assigned to G. diffusa.^[1]

Distribution

The species is endemic to an area between the Orange River on the border with Namibia in the north to Clanwilliam, Western Cape in the south. This area has cool rainy winters and dry hot summers.^[1]

Ecology

The flower heads of Gorteria diffusa are visited by several insect species which are not choosy, such as honey bees and monkey beetles, but also by a specialist species of bee fly Megapalpus capensis (synonym M. nitidus). The raised spots that can often be found on few or all of the ray florets, are strongly reminiscent of the fly's body. The absence of the spots results in fewer visits by Megapalpus males, but this does not impact on the setting of the seed. The flies are not attracted to simple black spots. Scientists conclude that the spots are an example of mimicry of the pollinator, that result in more visits by male specimens of the pollinator that are deceived into thinking the spots are females; G. diffusa is not unique in doing this, but it is a phenomenon largely restricted to orchids.^[4]^[5] Like the other species of Gorteria, the cypselas do not part from the flower head when ripe, but initially mostly only one germinates while remaining in the flower head. In G. diffusa, it has been observed that the other cypselas germinate in later years, thus making it possible to bridge periods of drought, when seed setting may not succeed.^[1]

Related Research Articles

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Polyarrhena is a genus of low, branching shrublets that is assigned to the daisy family. Its stems are alternately and densely set with entire or somewhat toothed leaves. Like in almost all Asteraceae, the individual flowers are 5-merous, small and clustered in typical heads, and which are surrounded by an involucre of in this case three whorls of bracts. In Polyarrhena, the centre of the head is taken by yellow disc florets, and is surrounded by one single whorl of white ligulate florets that have a pinkish-purple wash on the underside. These florets sit on a common base and are not individually subtended by a bract. The species occur in the Cape Floristic Region. Polyarrhena reflexa has long been cultivated as an ornamental and is often known under its synonym Aster reflexum.

Gorteria is a genus of small annual herbaceous plants or shrubs, with 8 known species, that is assigned to the daisy family. Like in almost all Asteraceae, the individual flowers are 5-merous, small and clustered in typical heads, and are surrounded by an involucre, consisting of in this case several whorls of bracts, which are merged at their base. In Gorteria, the centre of the head is taken by relatively few bisexual and sometimes also male, yellow to orange disc florets, and is surrounded by one complete whorl of 5–14 infertile cream to dark orange ray florets, sometimes with a few ray florets nearer to the centre. None, some or all of them may have darker spots at their base. The fruits remain attached to their common base when ripe, and it is the entire head that breaks free from the plant. One or few seeds germinate inside the flower head which can be found at the foot of plants during their first year. The species flower between August and October, except for G. warmbadica that blooms mostly in May and June. The species of the genus Gorteria can be found in Namibia and South Africa.

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Catananche lutea, is a woolly annual plant, in the family Asteraceae, with most leaves in a basal rosette, and some smaller leaves on the stems at the base of the branches. Seated horizontal flowerheads develop early on under the rosette leaves. Later, not or sparingly branching erect stems grow to 8–40 cm high, carrying solitary flowerheads at their tips with a papery involucre whitish to beige, reaching beyond the yellow ligulate florets. Flowers are present between April and June. This plant is unique for the five different types of seed it develops, few larger seeds from the basal flowerheads, which remain in the soil, and smaller seeds from the flowerheads above ground that may be spread by the wind or remain in the flowerhead when it breaks from the dead plant. This phenomenon is known as amphicarpy. The seeds germinate immediately, but in one type, germination is postponed. It naturally occurs around the Mediterranean. Sources in English sometimes refer to this species as yellow succory.

Felicia echinata, commonly known as the dune daisy or prickly felicia, is a species of shrub native to South Africa belonging to the daisy family. It grows to 1 m (3.3 ft) high and bears blue-purple flower heads with yellow central discs. In the wild, it flowers April to October.

Oedera capensis is a prickly shrublet belonging to the family Asteraceae. It has stems that branch only at the foot and are densely set over their entire length with narrowly triangular leathery leaves with a sharp tip at approximately right angles to the stem. At their tip are what at first sight appears to be a single flowerhead with yellow ray florets and yellow disc florets. In fact, these are mostly nine densely cropped heads, as is suggested by the nine domes of the "disc" of the composite head, the untidy arrangement of the ray florets, and becomes very clear when cutting through the composite head. It is an endemic of the south of the Western Cape province in South Africa.

Geissorhiza melanthera is a small perennial plant of 14–18 cm high that is assigned to the family Iridaceae. It survives the dry southern summer through storage of its resources in a corm. The stem carries two or three erect, sticky leaves of up to 18 cm (7 in) long, H-shaped in cross-section. This species blooms with six to twelve bilaterally symmetrical flowers, in a spike. Sometimes the spike has one side branch with fewer flowers. Each flower has six pale beige perianth lobes, a purple-red ring around a purple red tube and three blackish stamens. Each flower is subtended by two 1.25–2.25 cm long green bracts. This species flowers from the end of September till mid October. It is an endemic of the western slopes of the Piketberg mountains in the Western Cape province of South Africa.

Felicia josephinae is a roughly hairy annual herbaceous plant of 15–20 cm (6–8 in) high, that is assigned to the family Asteraceae. It branches near its base, and has few leaves along its stems. The lower leaves are set oppositely, inverted lance-shaped, relatively large at 3–7 cm long and ⅔–1¼ cm wide, and soon withering, while the higher ones are smaller and relatively narrower. In the axils of the leaves grow flower heads of 7–8 mm wide on stalks of up to 5 cm (2.0 in) long, topped with an involucre of about 5 mm (0.20 in) high and 4 mm (0.16 in) wide, consisting of eleven to thirteen bracts in two rows with bristles near the tip, eight to nine white or cream-coloured ligulate florets surrounding fourteen or fifteen deep purple disc florets. Flowers can be found in September and October. The species is an endemic species that can only be found in a small area along the west coast of the Western Cape province of South Africa.

Mairia crenata is a perennial herbaceous plant of mostly 2–15 cm (1–6 in) high that is assigned to the family Asteraceae. It has a woody rootstock of up to 5 cm (2 in) long, from which brown, fleshy roots develop. The five to eighteen, hard and leathery, spoon-shaped leaves are in one to three rosettes, have a distinct main vein, blunt or pointy tip, often dark red or blackish margins with rounded teeth and a ½–2 cm (0.2–0.8 in) long stalk-like foot, often initially somewhat woolly hairy, on particularly the lower surface and the main vein, but this is easily rubbed off the shiny surfaces. Each rosette produces mostly one, sometimes up to four, mostly rusty or whitish woolly hairy, brown or dark red inflorescence stalks, usually 1½–15 cm long, each with two to eight, initially woolly, line-shaped to oval bracts, the lowest up to 3 cm (1.2 in), decreasing size further up, and carrying mostly one, rarely up to three flower heads. The flower heads have a bell-shaped involucre with about 40 bracts, sixteen to thirty three violet to white ray florets of about 1¼–1⅞ cm long, and many yellow disc florets. The species flowers anywhere between February and December but only after a fire has destroyed the overhead biomass or serious disturbance. It is an endemic species that is restricted to the Eastern Cape and Western Cape provinces of South Africa.

Felicia heterophylla is a roughly hairy annual plant in the family Asteraceae. It has alternate leaves of 1–5 cm long with an entire margin or few inconspicuous teeth. The flower heads are set individually at the tip of its stems, and contain a whorl of purplish blue ray florets around a center of blackish blue disk florets. Flower heads appear in winter and spring. It is called true-blue daisy in English and bloublomastertjie in Afrikaans. It is an endemic species that only occurs in the Western Cape province of South Africa.

Felicia macrorrhiza is a small, evergreen shrub in the family Asteraceae. This species grows in the Karoo region of South Africa. It is called Aspoestertjie in Afrikaans.

Felicia amoena is a variably hairy, sometimes glandular, biennial or perennial plant, of about 25 cm (10 in) high, that is assigned to the family Asteraceae. It is somewhat woody at its base, roots at the nodes if these contact the soil, and has ascending branches. The leaves are oppositely arranged along the stems at and just above a branching fork, further up the leaves alternate. The flower heads sit individually on up to 12 cm long stalks. They are 2–3 cm in diameter and consist of about twelve to twenty five heavenly blue ray florets that surround many yellow disc florets. Three subspecies have been recognised, that differ in width of the leaves and the involucral bracts, the size of the heads and number of ray florets and in having glandular hairs. These can be found in coastal sands and inland areas in the Western Cape and Eastern Cape provinces of South Africa. Flower heads can be found from June till October.

Mairia coriacea is a perennial plant assigned to the family Asteraceae. It has broad, tough and leathery, evergreen leaves. These have a narrowed foot and an entire margin or a few shallow, irregular teeth. They grow in a rosette directly from the rootstock. The plant produces flower heads with one whorl of white to mauve ray florets around many yellow disc florets, with one or few on top of a dark reddish, woolly stalk. Flower heads appear after the overhead vegetation burnt down, often destroying the leaves in the process. It can be found in the southern mountains of South Africa's Western Cape province. It is called leather leaves in English.

Mairia petiolata is a tufted, variably hairy, perennial plant of up to 15 cm (6 in) assigned to the family Asteraceae. Its leaves are in a ground rosette, and have a stalk of mostly 2–5 cm long and an inverted egg-shaped to elliptic, 61⁄2–9 cm (2.6–4.6 in) long and 2–3 cm wide leaf blade, with a toothed margin. It mostly has two flower heads at the tip of the branches of each erect, dark reddish brown scape. The flower heads have a bell- to cup-shaped involucre that consists of 20–24, purplish, overlapping bracts in 3–4 whorls. These protect 12–16 pink, ray florets, surrounding many yellow disc florets. This species was only seen flowering once, in December. It is known from one location in the Langeberg, Western Cape province of South Africa.

Mairia hirsuta is a tufted perennial, herbaceous plant of up to 40 cm high, that is assigned to the family Asteraceae. Most of its narrow to broad elliptic or inverted egg-shaped leaves are part of the basal rosette, have margin that is rolled under, with rounded or pointy teeth or with some peg-like extensions, lightly woolly on the upper surface and densely woolly on the underside, but always the green remains visible. Flower heads have been found from July to November, mostly after a fire or when the soil has been disturbed. The species can be found in the southern mountains of the Western Cape province of South Africa.

Felicia clavipilosa is an upright, richly branched shrub of up to 60 cm (2 ft) high, that is assigned to the family Asteraceae. It has alternately arranged leaves, and flower heads with 3–4 whorls of involucral bracts with many yellow disc florets in the centre. Very characteristic for the species are the short club-shaped hairs on its fruits. There are two subspecies. Subsp. clavipilosa has narrowly lance-shaped entire leaves with one vein and pale mauve ray florets. Subspecies transvaalensis has lance-shaped leaves with one or three veins and white ray florets. The species occurs in southern Africa, with subsp. clavipilosa having a western distribution in Zambia, Zimbabwe, Namibia, Botswana and South Africa, and subsp. transvaalensis restricted to the east, from Zimbabwe, through Botswana to South Africa. The subspecies transvaalensis is sometimes called pokkiesblom in Afrikaans.

Felicia cana is a low and slender shrublet of up to 15 cm high, covered in white felty hairs, that is assigned to the family Asteraceae. It has alternately arranged leaves, and flower heads of about 16 mm (0.63 in) across, with 3–4 whorls of involucral bracts, and about 20 blue purple ray florets, surrounding many yellow disc florets in the centre. Very characteristic for the species are also the middle-long hairs with forked tips on the surface of its fruits. It is an endemic species that is restricted to a zone along the southern coast of the Western Cape province of South Africa.

Felicia tenella is an annual, sometimes biennial, herbaceous plant that may be slightly woody at its base, of 5–70 cm tall, that is assigned to the family Asteraceae. The species is very variable in size and hairiness. Its branches may be erect or ascending, and the leaves are narrowly line-shaped, 2–5 cm long and about 1 mm (0.04 in) wide. The leaves have a callous tip, lack visible nerves, and are mostly rigidly ciliate. The flower heads sit individually at the tip of stalks, have an involucre of three whorls of bracts, and about thirty light blue ray florets surrounding many yellow disc florets. Four subspecies are recognised. The species naturally occurs in the Northern Cape and Western Cape provinces of South Africa.

Felicia is a genus of small shrubs, perennial or annual herbaceous plants, with 85 known species, that is assigned to the daisy family. Like in almost all Asteraceae, the individual flowers are 5-merous, small and clustered in typical heads, and which are surrounded by an involucre of, in this case between two and four whorls of, bracts. In Felicia, the centre of the head is taken by yellow, seldom whitish or blackish blue disc florets, and is almost always surrounded by one single whorl of mostly purple, sometimes blue, pink, white or yellow ligulate florets and rarely ligulate florets are absent. These florets sit on a common base and are not individually subtended by a bract. Most species occur in the Cape Floristic Region, which is most probably the area where the genus originates and had most of its development. Some species can be found in the eastern half of Africa up to Sudan and the south-western Arabian peninsula, while on the west coast species can be found from the Cape to Angola and one species having outposts on the Cameroon-Nigeria border and central Nigeria. Some species of Felicia are cultivated as ornamentals and several hybrids have been developed for that purpose.

References

1 2 3 4 5 6 7 8 Stångberg, Frida; Anderberg, Arne A. (2014). "Morphology and taxonomic reclassification of Gorteria (Asteraceae)". Willdenowia . 44 (1): 97–120. doi: 10.3372/wi.44.44112 . JSTOR 24750917. S2CID 85280498.
↑ "Beetle Daisy". Red List of South African Plants. SANBI . Retrieved 2018-02-12.
↑ Sluiter, Liesbeth; Schaminée, Joop (2012). Kroonjuwelen van de Kaap [Crown Jewels of the Cape] (in Dutch). KNNV Uitgeverij. pp. 14–15.
↑ Johnson, S.; Midgley, J. (1997). "Fly pollination of Gorteria diffusa (Asteraceae), and a possible mimetic function for dark spots on the capitulum". American Journal of Botany . 84 (4): 489. doi:10.2307/2446018. JSTOR 2446018. PMID 21708596.
↑ Ellis, Allan J.; Johnson, Steven J. (2009). "The evolution of floral variation without pollinator shifts in Gorteria diffusa (Asteraceae)". American Journal of Botany . 96 (4): 793–801. doi:10.3732/ajb.0800222. PMID 21628234.

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[FSAA-1] 1 2 3 4 5 6 7 8 Stångberg, Frida; Anderberg, Arne A. (2014). "Morphology and taxonomic reclassification of Gorteria (Asteraceae)". Willdenowia . 44 (1): 97–120. doi: 10.3372/wi.44.44112 . JSTOR 24750917. S2CID 85280498.

[2] "Beetle Daisy". Red List of South African Plants. SANBI . Retrieved 2018-02-12.

[3] Sluiter, Liesbeth; Schaminée, Joop (2012). Kroonjuwelen van de Kaap [Crown Jewels of the Cape] (in Dutch). KNNV Uitgeverij. pp. 14–15.

[4] Johnson, S.; Midgley, J. (1997). "Fly pollination of Gorteria diffusa (Asteraceae), and a possible mimetic function for dark spots on the capitulum". American Journal of Botany . 84 (4): 489. doi:10.2307/2446018. JSTOR 2446018. PMID 21708596.

[5] Ellis, Allan J.; Johnson, Steven J. (2009). "The evolution of floral variation without pollinator shifts in Gorteria diffusa (Asteraceae)". American Journal of Botany . 96 (4): 793–801. doi:10.3732/ajb.0800222. PMID 21628234.

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