Taxa treated:
Cuphea ignea
C. lanceolata
C. ×purpurea
C. viscosissima
Lythrum acutangulum
L. hyssopifolia
L. junceum
L. portula
L. salicaria
L. ×scabrum
L. thymifolia
L. virgatum
Punica granatum
Trapa natans
References
Key to genera
Key to Lythrum
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Lythraceae Taxa treated:
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 © Flora Nordica

by Thomas Karlsson
(6b, 20071112)

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This treatment is partly outdated - the final version will appear in print.
The family Lythraceae comprises also the former Punicaceae and Trapaceae, a taxonomic view supported by recent molecular studies (Graham et al. 1998). Genera in the family are in general well delimited and homogeneous. The genus Peplis L. is here included in Lythrum (in accordance with Webb 1967), due to the apparent morphological continuity between them; however, palynological characters suggest that Peplis should be distinguished (Graham et al. 1987), and a closer investigation is needed.
1 Floating aquatic; leaves with rhombic, dentate blade
2. Trapa
- Erect or creeping, terrestrial plants (often on damp soil); leaf blades distinctly longer than wide, with entire margin
2
2 Glabrous shrub
1. Punica
- Herb
3

3 Hypanthium strongly gibbous; plant glandular all over and with red, coarse bristles
4. Cuphea
- Hypanthium not gibbous; plant glabrous or with white, eglandular hairs

1. Punica L.

Linnaeus, Sp. pl.: 472 (1753).

Punica granatum L. 1753. D Granatæble. F granaattiomena. N granateple. S granatäpple. – Deciduous shrub or small tree. Young shoots with 4 narrow wings, glabrous, flushed with red. Leaves opposite, distinctly articulate towards the stem, without stipules; petiole c. 1 mm; blade 16–25 ´ 4.5–7 mm, lanceolate, broadly acute, entire, coriaceous, glabrous, with a strong midrib; lateral veins forming loops (thus not reaching the margin). Flowers (not present in Nordic material) terminal, epigynous, actinomorphic, with 5–8 sepals and petals, to 5 cm diam.; hypanthium and calyx dark red, petals a brilliant red; stamens numerous; pistil 1. Fruit globose, to 10 cm, red, with a woody wall and subdivided into several cells, each containing numerous seeds with a fleshy testa. – [2n=16]
A food refuse casual. S Sk Vankiva 2006, Srm Eskilstuna 2003, Grödinge 2004, Upl Ed 2003–2005. – From Iran to the Himalaya; cultivated in warm areas worldwide; naturalized since ancient times at least in the eastern Mediterranean. - Map (not in the book).

2. Trapa L.

Linnaeus, Sp. pl.: 120 (1753).

Trapa natans L.       Map

Linnaeus, Sp. pl.: 120 (1753). – Type: Italy, Mantova (Lago Superiore), 20.IX.1904 Fiori 471 (K) neotype, sel. by Verdcourt in Kew Bull. 41: 448 (1986).

D Hornnød. F vesipähkinä. N vassnøtt. S sjönöt.

Literature. Korhola & Tikkanen 1997, Malmström 1920, Nathorst 1888.

Hydrophyte. Summer-annual. Stem 0.5–2 m, submerged, sometimes branched from the cotyledonary node, terete, glabrous, in the lower and middle parts thin and with 4–12 cm long internodes, towards the apex 6–12 mm thick and with extremely short internodes. Adventitious roots in lower stem parts simple, growing downwards and rooting the plant in the bottom; those in middle parts reminiscent of Myriophyllum leaves, in pairs or groups from the nodes, densely pinnately branched (branches in 4 rows), growing outwards and containing chorophyll. Leaves alternate (lowermost ones opposite). Submerged leaves filiform, to 6 cm, glabrous, soon decaying. Floating leaves 15–35, forming a rosette; stipules 2.5–3 mm, narrowly triangular, whitish, ephemeral; petiole 3–10.5 cm (in outer leaves; in inner leaves gradually shorter), with age and especially in fruiting specimens spindle-shaped and with air-filled parenchyma in the upper third, with sparse to fairly dense, multicellular, ± brownish hairs; blade rhombic, 2.1–4 ×1.9–4.1 cm, 0.8–1.1 times as long as wide, coriaceous; proximal edges entire; distal edges sharply dentate from slightly curved teeth which are bifid at the very apex; upper surface glabrous and glossy, usually ± red; lower surface at first hairy like the petiole but later on becoming glabrous, green with paler veins.
Flowers single, axillary, bisexual. Pedicel hairy like the petioles, after anthesis elongating to 11–15 mm and becoming deflexed. Sepals 4, 3.3–4 mm, narrowly triangular to lanceolate, acute, coriaceous, keeled, ± glabrous, enlarging and persisting in fruit, each developing into a stiff horn-like spine. Petals 4, white, 5.5–6.5 × 3–4 mm, obovate, slightly longer than the sepals, caducous. Stamens 4, alternating with the petals, 3–3.2 mm; anther 1.3 mm. Ovary semi-inferior, surrounded by a crenulate disc. Style 2.2–2.3 mm, caducous; stigma capitate. Fruit a hard-walled, blackish grey nut, surrounded by the brownish to olive receptacle which is 2.5–3 cm long and wide, slightly flattened in the transversal plane and provided with 4 horn-like, glochidiate spines (formed by the sepals) and an apical rim or crown (developed from the disc); lateral spines directed obliquely upwards, median ones outwards or slightly downwards. – Mid-summer to autumn.
[2n=c. 36, c. 48]
Distribution. Nem(–BNem). Indigenous; now extinct. S Sk Hjärsås (Ranviken in the lake Immeln), first recorded in 1871 and last seen in 1915; Klm Misterhult 4 lakes lying closely together (Bosjön, Fagersjön, Hemsjön (=Sulegångssjön) and Älmten), first recorded från Hemsjön by Linnaeus (1745) and last seen there in 1800, from the other three lakes reported in the 1770’s.
Records from some other places in southern S have also been published but are not accepted here: SmI Bottnaryd 1774 (probably subfossil; Malmström 1920); SmI Vederslöv 1847 (probably cultivated, possibly brought in by German soldiers; Svensson 1920); Klm Kråksmåla (Nordstedt 1920; a misunderstanding of “Kåksmåla” in Linnaeus (1745) which refers to the Misterhult localities). An 18th century record from the lake Hökasjö in Klm Långemåla is probably a legend only (Svensson 1920); Hökasjö has also incorrectly been referred to the parishes of Lemnhult (Linnaeus 1745) and Skede (Pontén 1847).
Subfossil fruits have been found in interglacial deposits in D Jylland. Finds in postglacial deposits have been made in eastern D (Sjæ and LFM Lolland), southern S (north to central Vrm, Vsm, Upl and Gst, but not known from Gtl) and southern and central F (north to KP and PS). The species was, however, not evenly distributed within this area. The lack of subfossil Trapa in southern Klm probably reflects that sufficiently nutrient-rich lakes have not existed in these areas, whereas its absence from the higher parts of the south Swedish uplands rather has climatic reasons.  Generally, its former distribution in Norden reflects the slightly continental total distribution.
The species apparently arrived relatively early in the Postglacial and reached its maximum distribution and frequency during the Boreal climatic optimum c. 3.000­–2.500 years ago. During the climate deterioration in Atlantic time it declined rather rapidly throughout its Nordic area; however, in most cases the direct cause of its extinction was probably not climatic change itself but spontaneous filling-in of the eutrophic and relatively productive lakes where it thrived. The occurrences known from historical times are to be viewed as relictual, being dependent on extremely favourable local conditions. These vulnerable populations were harmed by the intensive collecting activity.
Trapa natans (in a moderately wide sense) is known in historical time from C and S Europe from Spain and France in the west, Latvia in the north and eastern C Russia in the east, from N, SW and E Africa and SW Asia. It is strongly declining in Europe and has become extinct in many areas; in EU it is protected under the Bern convention. – The species is known as an established alien from NE USA (where it has become invasive) and SE Canada.
The fruits of Trapa natans are edible and in areas with more common occurrence they have sometimes been collected for food. Trapa fruits were also collected and used by Neolithic man. Closely related or possibly conspecific taxa of Trapa are cultivated for food in tropical Asia.
Habitat. Warm and nutrient-rich, often humic but not calcareous freshwater, in small lakes and sheltered inlets with mud-bottom; usually together with Nuphar lutea or Nymphaea alba.
Biology. Flower development apparently only takes place if the water temperature reaches 20°C. The flowers usually open in the air but wither after some hours only. Soon after anthesis the pedicel bends downwards and the fruit matures in the water. The fruits are heavy and fall to the bottom when ripe; floating fruits are empty. The dispersal ecology of Trapa is poorly understood; the fruits do not seem very apt for dispersal over distances. Possibly the species is spread mainly through whole plants which float away or become transported with animals.
Variation. Swedish specimens are on average smaller than C and S European ones; they have smaller and less hairy leaves with blades almost always widest at the middle, (almost) glabrous sepals and smaller petals. These differences may, at least partly, be due to the fact that the populations grew under less favourable circumstances. The population in S Sk Hjärsås was probably unique in having almost hypogynous flowers with the spines (which are unusually narrow) arising almost basally on the mature fruit. It was described as T. natans var. conocarpa F. Aresch. (Areschoug 1873). The population growing in S Klm Misterhult in historical time was probably similar (but no fully ripe fruits are known with certainty).
The subfossil material from Norden shows very wide variation (Nathorst 1888, Malmström 1920). The variation affects fruit size, number of horns (rarely 2 or 6) and their length and thickness, presence of outgrowths between the sepal horns (rare), proportion of fruit enclosed in the hypanthium, and development of a crown. Nuts which agree with those of recent stands in S Europe are present in the subfossil material, as well as such agreeing with material from Immeln in S Sk. Many lakes appear to have had a variant of their own, suggesting a low degree of exchange of genetic material through dispersal and cross-pollination.

3. Lythrum L.

Linnaeus, Sp. pl.: 446 (1753).Peplis L. (1753).
Annual or perennial herbs. Leaves entire, not petiolate or with a very short petiole, at least the lowermost ones opposite or verticillate. Flowers ± sessile or with extremely short pedicels, single or in axillary cymes, 5- or 6-merous (rarely 4-merous), actinomorphic or slightly zygomorphic, perigynous with a well-developed, cylindrical to cup-shaped, ± ribbed hypanthium. Bracteoles 2. Epicalyx usually present, often more prominent than the calyx. Petals (not always present) inserted at the mouth of the hypanthium, crumpled in bud. Stamens as many as or twice as many as the sepals. Style distinct; stigma capitate. Capsule of 2 carpels, ± enclosed in the hypanthium. Seeds numerous; testa almost smooth when dry, becoming rough and slime-covered when wetted.Chromosome base-number x=5. Polyploidy (diploids and dodecaploids in Norden).


1 Perennial; stems, leaves and calyx hairy; petals at least 7 mm; triheterostylous
- Annual; glabrous; petals 1–4 mm; homostylous
2
2 Leaves linear; hypanthium cylindrical
- Leaves spathulate or obovate; hypanthium cup-shaped

1. Lythrum salicaria L.        Map

Linnaeus, Sp. pl.: 446 (1753). – Type: Linnaean Herbarium 626.1 (LINN) lectotype, sel. by Nasir & Ali (ed.), Fl. W. Pakistan 78: 7 (1975).

D Almindelig Kattehale. F rantakukka. Fa ***. I ***. N kattehale. S fackelblomster.

Literature. Alm 1993, Frisendahl 1921, Holmboe 1936, Ljung 2007.

Hemicryptophyte. Perennial, (10–)30–150 cm, with thick, erect, woody stock producing one or several stems each year; triheterostylous. Stem erect, unbranched or branched in the upper and middle parts, usually hairy from short, patent hairs at least in the upper part, rarely villous or entirely glabrous, with 4–6 distinct ribs (sometimes developed into narrow wings); submerged parts of stem develop an aerenchymatous cortex (with large, gas-filled, brownish cells). Leaves almost sessile, opposite or sometimes in whorls of 3 (rarely alternate); lower ones narrowly ovate; middle ones (3.2–)4.2–11.4 × (0.7–)1–2.6 cm, 3–6(–9.5) times as long as wide, lanceolate to narrowly lanceolate or rarely narrowly ovate, with shallowly to deeply cordate base and acute, broadly acute or rarely obtuse tip; margin scabrid; upper surface dark green, glabrous, scabrid or with short hairs; lower surface a paler green, usually hairy from short or long, patent hairs (more rarely with single hairs along the veins only, or glabrous).
Inflorescence a spike-like, sometimes very dense thyrse; bracts lanceolate and acute to ovate and caudate (rarely elongated, similar to the upper stem leaves but smaller), 8–22(–27) mm; middle cymes with 3–11 flowers. Bracteoles linear, 4–9(–13) mm, thin and scarious, caducous. Flowers 5- or 6-merous; pedicel to 0.8 mm. Hypanthium (3.3–)4.7–8 mm, narrowly campanulate; veins 10 or 12, rib-like, hairy. Epicalyx segments 1.6–3.2(–4.1) mm, subulate, herbaceous, (1.4–)1.7–3.6(–5.2) times as long as the sepals. Sepals deltate, 0.8–1.4 mm, scarious, red-tinged. Petals reddish purple (rarely pink or white), narrowly oblanceolate to narrowly obovate, sometimes slightly unequal (lower ones slightly larger than the upper ones), longest ones 8.3–13.7 × 2.1–4.6 mm. Stamens 10 or 12, of two different lengths in each flower, directed slightly downwards but slightly upcurved distally; long stamens 8.7–13.7 mm, distinctly protruding, with blue pollen; medium stamens 6.5–8.1 mm, slightly longer than the hypanthium and epicalyx, with yellow pollen; short stamens 3.2–5.4 mm, enclosed in the hypanthium, with yellow pollen. Style in longistylous flowers 7.1–9.5 mm and distinctly protruding, in mesostylous ones 4.1–6.4 mm and slightly longer than the hypanthium, in brevistylous ones 1.4–1.8 mm and enclosed. Seeds 0.85–1(–1.25) × 0.33–0.55 mm, ovoid with one side slightly flattened, yellow-brown; surface faintly reticulate. – Mid-summer to late summer.
2n=60 (F V, N Vf, S Sk 3, Öl 2). – [2n=30, 60]
Distribution. Nem–BNem(–SBor). Alt. N NN (Trysil) 440 m. – D common throughout (perhaps slightly less so in central and parts of western Jylland). N common in the southeastern lowland north to He Trysil and Op Ringebu, and along the coast north to SF Askvoll, Fjaler and Gaular. S common north to central Vrm, southern Dlr and eastern Hls, near the coast and along the river Ljungan in Mpd, and along the coast from Ång to Nb (however, scattered in areas with large-scale agriculture, and rare in the poor and leached areas on the border SmI/Hl/Vg); scattered in central Dlr, western Hls, southwestern Jmt (Hällesjö, Ragunda and Stugun), and in the interior parts of the coastal provinces north of Hls. F common north to St and ES, fairly common north to Kn and PP, rare in western Ks and southern KiL.
Throughout Europe and W Asia; E Asia, NW Africa and Ethiopia; anthropochorous in the Americas (invasive in North America) and Australia.
Habitat. Wet or intermittently water-logged, not too base-poor ground, often in bouldery, stony or gravelly and usually light-open places; typically in rock crevices on lake or sea shores (in the Baltic to the outermost skerries), or along rivers and streams, especially at rapids. Also in more closed vegetation, e.g. alluvial meadows, tall-herb meadows, quaking fens, Salix scrub and other wet deciduous woodland. Strongly hemerophilous: ditches, ponds, marl-pits, formerly grazed or mown grassland; favoured by overgrowth. – Grown for ornament and sometimes escaped.
Biology. The flowers are visited primarily by bumblebees but also by honey-bees, syrphid flies and butterflies (Waites & Ågren 2004). The species is triheterostylous. Longistylous, mesostylous and brevistylous morphs differ in the relative position of stigmas and anthers in the flowers. An individual plant has flowers of one morph only. Full seed-set is only achieved if pollen is transferred between morphs and from anthers at the same level as the receiving stigma. The three morphs occur in almost equal frequency throughout the area; usually all three morphs are present in a local population (Halkka & Halkka 1974). – Spread almost exclusively by seed, which matures in six to eight weeks time.
Variation. Cultivation experiments have demonstrated a clinal latitudinal variation in phenology of growth and flowering, allocation of resources to winter buds, and length of the juvenile period (Olsson & Ågren 2002). Populations from higher latitudes started and finished above-ground growth earlier than populations of more southern origin. They also started to flower earlier and remained in flower for a shorter period, were older at first reproduction and tended to flower less frequently, and they produced larger and more numerous winter buds. – Many other vegetative (and floral) characters vary at random between and within populations. Especially striking is the variation in plant size, leaf shape, bract shape and amount and length of hairs on different parts. Usually at least the inflorescence axis and calyx are hairy; completely glabrous plants are extremely rare.
Similar taxa. Lythrum salicaria is similar to the rare casuals L. ×scabrum (L. salicaria × virgatum) and L. virgatum.

2. Lythrum hyssopifolia L.        Map

Linnaeus, Sp. pl.: 447 (1753). – Type: Burser Herbarium XII:93 (UPS) lectotype, sel. by Lourteig in Fl. Ecuador 37: 1 (1989).

D Græskattehale. F iisoppirantakukka. Fa ***. I ***. N møllekattehale. S dvärgfackelblomster.

Therophyte. Glabrous, bluish green annual, 5–40 cm; homostylous. Stem erect or ascending, narrowly winged from the decurrent leaf-bases, unbranched or with ascending branches. Leaves alternate (the lowermost ones often opposite), 8–17 × 1–3.5 mm, suberect, lowermost ones narrowly elliptic, middle and upper ones narrowly oblong to linear with cuneate to rounded base and obtuse or broadly acute tip; margin smooth or slightly scabrid.
Flowers axillary, single, often produced along ± the whole shoot, 5- or 6-merous. Bracteoles narrowly triangular, 0.9–1.1 mm, hyaline, persistent. Hypanthium 4–5 mm, shorter than the subtending leaf, obconical in flower, cylindrical in fruit, sometimes diffusely reddish towards the base or more rarely with diffuse reddish dots; veins twice as many as the sepals, riblike and very prominent in flower, less so in fruit. Epicalyx segments 0.8–1.3 mm, subulate, herbaceous, 1.8–2.2(–3) times as long as the sepals. Sepals deltate, (0.4 –)0.5–0.6 mm, scarious. Petals red with a paler base, oblanceolate to obovate, 2.6–3.4 × 1.2–1.5 mm. Stamens 5–6, not protruding, 2.1–2.8 mm. Style 1.7–2.1 mm, initially concealed but later on protruding due to the growth of the fruit. Capsule cylindrical, 4–4.5 × 1.5 mm, as long as the hypanthium, blackish brown, thick-walled, opening with 2 valves. Seeds 0.85–0.95 × 0.55–0.7 mm, ovoid with one side slightly flattened, pale to dark brown; surface faintly reticulate. – Summer.
[2n=20]
Distribution and habitat. A casual alien on disturbed or temporarily wet ground, brought in with, e.g., ballast, cereals, cork, timber and wool; few records after 1970. D ØJy Vejle 1956, Sjæ Amager 1894, Avedøre 1980, København 1927, 1929, 1930, Sorø 1951, 1962, 1963 (with cork). mainly at mills; Ak Frogn 1930 (garden weed), Oslo 1927, Bu Hurum 1995 and 2004 (with timber), VA Kristiansand 1967–68, Ro Stavanger 1967, Strand 1967, Ho Bergen 1943, Lindås 1927, Osterøy 1927, Stord 1920, Vaksdal 1927, ST Skaun 1932, 1937, Trondheim 1971. S Sk Lackalänga c. 1950 (with wool), Landskrona 1968, Öl Föra 2003–04 (temporarily wet sandy ground), BhG Angered 1941, Mölndal 1936, Göteborg 1941, 1955–56, Uddevalla 1937, Ög Dagsberg 1967, Gst Gävle 1929 (docks), Mpd Skön 1914 (ballast). F U Helsinki (Lauttasaari) 1940 (with cork from Morocco), EH Hämeenlinna 1960 (fur factory), Tampere (Viinikka) 1983 (railway yard). – A report from D ØJy Slagelse (Larsen & Pedersen 1960) was based on specimens of L. junceum, and a report from S Srm (Rydberg & Wanntorp 2001) on a specimen of L. acutangulum. There is no voucher for the report from D LFM Nysted (Larsen & Pedersen 1960).
Europe (except the northern parts), western Asia, North Africa, Ethiopia and South Africa; anthropochorous in the Americas and Australia.
Similar taxa. Lythrum hyssopifolia is similar to the rare casuals L. acutangulum, L. junceum (both triheterostylous) and L. thymifolia (homostylous, with 4-merous flowers).

3. Lythrum portula (L.) D.A. Webb        Map

Webb, Feddes Repert. 74: 13 (1967). – Peplis portula L., Sp. pl.: 332 (1753). – Type: Linnaean Herbarium 128, sphalmate ’38’ (LAPP) lectotype, sel. by Chamberlain in Regnum Veg. 127: 4 (1993).

D Vandportulak. F ojakaali. Fa **. I **. N vasskryp. S rödlånke.

Therophyte (summer-annual). Glabrous; stem and shoot-apices often tinged red; homostylous. Stem 6–27 cm, longest in submerged plants, decumbent, rooting at the nodes, weakly 4-angled, usually branched at least in the lower part (branches often develop in nodes with a flower, between the flower and the bract); internodes often slightly swollen, in submerged plants very elongated. Leaves opposite or sometimes subopposite, (4.8–)6.3–16.2 mm, brownish green, slightly glossy, spathulate; narrow basal part 1.6–5.5 mm; widened upper part suborbicular to broadly oblanceolate, (3.1–)4.8–11.5 × 2.1–8.4 mm, with broadly rounded apex; margin smooth., (3.1–)4.8–11.5 × 2.1–8.4 mm, with broadly rounded apex, brownish green, slightly glossy; margin smooth.
Flowers axillary, single, almost sessile, produced along ± the whole shoot, 6-merous. Bracteoles very narrowly triangular (almost filiform), 0.7–1.2 mm, hyaline, persistent. Hypanthium 1.1–1.7 mm in fruit, much shorter than the subtending leaf, cup-shaped, pale, with 12 green (or sometimes reddish) veins, which are not raised. Epicalyx segments 0.2–0.8(–1) mm, subulate, herbaceous, 0.2–0.8 times as long as the sepals (in exceptional cases longer than the sepals). Sepals triangular, acuminate, pale and translucent except along the veins, with a dark, thickened tip, 0.8–1.1 mm. Petals usually absent; if present 1­–6, pink, clawed, caducous, 0.5–0.7 × 0.4–0.6 mm. Stamens 6, not protruding, 0.8–1.1 mm. Style 0.15–0.3 mm. Capsule globose, 1.7–2.4 mm, protruding from the hypanthium, thin-walled and translucent but usually tinged red in the exposed part, opening irregularly. Seeds 0.55–0.67 × 0.4–0.5 mm, ovate in outline, with one convex side (pale yellow) and one flat or concave side (slightly darker); surface even. – Mid-summer to late summer.
2n=10 (S Sk). – [2n=10]
Distribution. Nem–SBor(–MBor). – D scattered to fairly rare in Jylland and Brn, elsewhere rare. N scattered to rare in the eastern lowlands north to He Grue and Op Gran, and west to VA Flekkefjord; Ro Time, Sola, Sandnes and Rennesøy; declining throughout. S scattered north to central Vrm, eastern Vsm and Upl (but fairly rare in the highlands of northwestern SmI and eastern Vg); fairly rare in Öl, western Vsm, southern and central Dlr, and Gst; rare in Hls (12 localities); Mpd Selånger (last c. 1900), Ång Härnån 1840, c. 1950, Säbrå 1988 and Styrnäs 1988, Vb Skellefteå 1919, Nb Nederkalix 2001 and LyL Sorsele 2004; not known from Gtl. Declining in several areas due to less intense grazing and overgrowth; river regulations for hydroelectric power have spoilt many occurrences in Dlr. F scattered to rare in the south; probably casual in PK Liperi 1998 and KP Kokkola 1868, 1917.
Europe (except the northernmost parts) and North Africa; anthropochorous in the Americas.
Habitat. Bare, damp or periodically water-logged, nutrient-poor to fairly nutrient-rich mineral soil (sand to clay) in light-open situations; apparently calcifuge but strongly favoured by trampling and grazing. Shores of lakes and rivers, sometimes together with Limosella aquatica and Subularia aquatica; near the sea in dune slacks and rock-pools; more common and widespread in man-made habitats, e.g. pools and ponds in pastures, damp paths and gravel-pits, in such places often with Anagallis minima, Gypsophila muralis and Radiola linoides; rarely a weed in water-logged arable fields. Especially as a terrestrial plant erratic, after periods of inundation sometimes occurring in large numbers.
Biology. Evidently largely self-pollinated; the stigmas are receptive (and sometimes loaded with pollen) already in bud. Submerged plants produce flowers but usually no mature fruits.
Variation. The epicalyx segments are fairly variable in length but generally within the range of ssp. portula (Allen 1954). The specimen from the very isolated locality in S LyL deviates in having considerably longer epicalyx segments (1 mm, much longer than the calyx lobes) and is intermediate to ssp. longidentata (J. Gay) P.D. Sell, a taxon with a SW European coastal distribution, and is probably a casual introduction.
Similar taxa. Lythrum portula is sometimes confused with Callitriche stagnalis which, however, has completely different flowers and fruits; further, Callitriche has thin leaves, with very small hairs (appearing as dots) on both surfaces (Lythrum portula is fairly thick-leaved and completely glabrous).

Rare casuals

Lythrum acutangulum Lag. 1816. S vingfackelblomster. – Small, slender, glabrous, ± erect annual; triheterostylous. Leaves linear, 6–7 mm, acute, with cuneate base. Flowers axillary, 6-merous. Hypanthium longer than the subtending bract, tapering towards the base, without red dots; the veins ending in the epicalyx segments narrowly winged. Epicalyx segments twice as long as the sepals. Petals c. 5 mm, red with a white base. [2n=10]
S Srm Brännkyrka (Gubbängen) 1997 (ruderal ground). – France, Spain, NW Africa. - Map (not in the book).
Lythrum junceum Banks & Sol. in Russell 1794. D ***. F kimppurantakukka. S småfackelblomster. – Small, slender, glabrous, decumbent to ascending annual or short-lived perennial; triheterostylous. Leaves linear, 9–11 mm, broadly acute, with cuneate base. Flowers axillary, 6-merous. Hypanthium shorter than the subtending bract, tapering gradually towards the base, not winged but with distinct red dots in the lower part. Epicalyx segments as long as the sepals or slightly longer. Petals c. 6 mm, red with a white base. [2n=10]
D ØJy Aarhus 1962, Randers 1924–25 (docks), FyL Odense 1964 (with bird-seed), Sjæ Amager 1970, København 1927, 1963 (docks, in 1927 with Mediterranean fruit), Slagelse 1958 (docks), Sorø 1951, 1962, 1963 (with cork). S BhG Göteborg 1942–44, Angered 1941, Jmt Östersund 1930. F U Helsinki (Lauttasaari) 1940, 1947 (with cork from Morocco). - Map (not in the book).
Lythrum ×scabrum Simonk. 1877 (L. salicaria × virgatum). D ***. F tarharantakukka. N hagekattehale. S hybridfackelblomster. Differs from L. salicaria (1) in having narrower leaves, a narrow inflorescence with few-flowered (or partly one-flowered) cymes, and longer sepals. Distinguished from L. virgatum (rare casual) by relatively wider leaves with almost truncate base, less narrowly acute leaf apex, scabrid stems, leaves and hypanthium, and epicalyx segments which are longer than the sepals.
Grown for ornament. N He Ringsaker (Grefsheim) 2001 (throwout from nursery). - Map (not in the book).
Lythrum thymifolia L. 1753. F timjamirantakukka. S barrfackelblomster. – Small, slender, glabrous or slightly scabrid, ± erect annual; homostylous. Leaves linear, 4–6 mm, usually less than 1 mm wide, obtuse. Flowers axillary, 4-merous. Hypanthium shorter than the subtending bract, cylindrical, neither winged nor red in the lower part. Epicalyx segments much longer than the sepals. Petals c. 1.5 mm, red. [2n=10]
F U Helsinki (Lauttasaari) 1940 (with cork from Morocco). - Map (not in the book).
Lythrum virgatum L. 1753. D Smalbladet Kattehale. F etelänrantakukka. N prydkattehale. S smalt fackelblomster. – Tall, glabrous, erect perennial. Leaves narrowly lanceolate, with narrowly cuneate base and acute tip; margin scabrid. Inflorescence a narrow thyrse with few (sometimes single) flowers in each cyme. Flowers 6-merous, triheterostylous. Hypanthium cylindrical; epicalyx segments not or only slightly longer than the sepals. Petals 7–9 mm, red. – [2n=40]
Grown for ornament; persisting on throwout or sometimes escaped; also a grass seed alien. D Sjæ Gentofte 1962–63, Brn Rø 1990. N Ak Oslo 1940, Te Drangedal 1952 (throwout), Vf Larvik 2002, AA Tvedestrand 1965. S Sk (Lilja 1870), BhG Göteborg 1934, Lundby 1961, Upl Täby 2003 (tip). – C and SE Europe, W Asia. - Map (not in the book).

4. Cuphea P. Browne

Browne, Civ. nat. hist. Jamaica: 216 (1756).

Literature. Graham 1988.

Annuals or perennials. Leaves entire, opposite. Flowers short-pedicelled, axillary (but pedicel connate with the stem, flower thus apparently emerging between the axils of the next node), 6-merous, strongly zygomorphic. Hypanthium cylindrical, with 12 strong ribs and an adaxial pouch at the base. Bracteoles 2. Epicalyx present. Petals inserted at the mouth of the hypanthium, the 2 uppermost the largest. Stamens 11. Style distinct. Capsule of 2 carpels, enclosed in the hypanthium, splitting longitudinally along the dorsal wall, the hypanthium also splitting, the seed-bearing placenta becoming erect, projecting out from the capsule and hypanthium.
Chromosome base-number x=8. Polyploidy and aneuploidy.
Cuphea ignea A.Br. 1849. D Små Kinesere. F tulitorvi. Fa . I . N krokbeger. S cigarrettglöd. – Small perennial (but annual when grown outdoors in Norden); glabrous (stems sometimes with a line of curled hairs). Leaves with petiole 6–8 mm; blade c. 35–45 × 14–20 mm, rhombic with attenuate base and acuminate apex. Hypanthium 18–22 mm, very narrow, bright red with dark purple apex; mouth whitish, with a fringe of long, coarse, glandular hairs. Calyx lobes 6, triangular, acute, about equal in size. Petals absent. Stamens of different length, 4 long-exserted, 5 shortly exserted, 2 enclosed; filaments black, glabrous.
Grown for ornament; rarely escaped. S Sk Kristianstad 1999 (tip). – Mexico. - Map (not in the book).
Cuphea lanceolata Aiton 1811. D . F . Fa . I . N . S. – Annual; stem, petioles and hypanthium densely covered with patent, coarse, red-based glandular hairs. Leaves with petiole 5–10 mm and blade lanceolate, c. 50 × 15 mm. Hypanthium 15–17 mm. Calyx lobes 6, triangular, acute, the uppermost one pale and much larger than the others. Petals 6, dark red, the 2 adaxial ones c. 12 mm, the rest c. 7 mm. Stamens not protruding; filaments densely woolly from lilac hairs. [2n=12]
Grown for ornament; rarely escaped. S Srm Tyresö (Bollmora) 2007. – Mexico. - Map (not in the book).
Cuphea ×purpurea Lem. 1848 (C. llavea Lexarza × procumbens Ortega). D . F . Fa . I . N . eldflugeblomster. – Similar to C. lanceolata but hairs of hypanthium partly whitish, erectopatent, filaments woolly from hairs which are partly whitish, partly lilac, and petals with a long, narrow claw (the teeth of the hypanthium therefore clearly visible in front view). [2n=9]
Grown for ornament; rarely escaped. S Bl Rödeby (Bubbetorp), tip, 2007. – A garden hybrid; parents from Mexico. - Map (not in the book).
Cuphea viscosissima Jacq. 1773. D . F . Fa . I . N . S indianbloss. – Annual; stem, petioles and calyx densely covered with patent, coarse, red-based glandular hairs. Leaves with petiole 6–8 mm and blade narrowly ovate, 20–22 × 8–12 mm. Hypanthium c. 10 mm. Calyx lobes 6, triangular, acute, the uppermost only slightly enlarged. Petals 6, dark red, the 2 adaxial ones 5 mm, the rest c. 2.5 mm. Stamens not protruding; at least the uppermost filaments woolly from lilac hairs. [2n=12]
A ley seed alien in S Hl Snöstorp (Nydala) 1884 (clover field). – E North America. - Map (not in the book).

References To top

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Graham, S.A. 1988: Revision of Cuphea section Heterodon (Lythraceae). Syst. Bot. Monogr. 20.
Graham, S.A., Nowicke, J. Skvarla, J., Graham, S., Patel, V. & Lee, S. 1987: Palynology and systematics of the Lythraceae. II. Genera Haitia through Peplis. Amer. J. Bot. 74: 829–850.
Graham, S.A., Thorne, R.F. & Reveal, J.L. 1998: Validation of subfamily names in Lythraceae. Taxon 47: 435–436.
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Waites, A.R. & Ågren, J. 2004: Pollinator visitation, stigmatic pollen loads, and among-population variation in seed set in Lythrum salicaria. J. Ecol. 92: 512–527.
Webb, D.A. 1967: Generic limits in European Lythraceae. Feddes Repert. 74: 10–13.

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