Ranunculus schmalhausenii Luferov (1997: 57)

Bobrov, Alexander A., Zalewska-Gałosz, Joanna, Jopek, Magdalena & Movergoz, Ekaterina A., 2015, Ranunculus schmalhausenii (section Batrachium, Ranunculaceae), a neglected water crowfoot endemic to Fennoscandia-a case of rapid hybrid speciation in postglacial environment of North Europe, Phytotaxa 233 (2), pp. 101-138 : 121-130

Ranunculus schmalhausenii Luferov (1997: 57)

≡ Ranunculus aquatilis var. dichotomus Schmalhausen (1874a: 47)

≡ Ranunculus dichotomus ( Schmalhausen (1874a: 47)) Orlova (1956: 289), non Mociño & Sessé ex Candolle (1818: 288)

≡ Batrachium dichotomum ( Schmalhausen (1874a: 47)) Trautvetter (1884: 363)

Type: RUSSIA, In See Kopenskoe in Kreise von Jamburg, 23 June 1873, Schmalhausen s. n. (Lectotype: LE!, isolectotype: LE!, designated here).

= Ranunculus peltatus var. septentrionalis Lindberg in Hjelt (1906: 228)

Type: FINLAND, Ab, par. Lojo, lac. Hormasjö, 17 July 1881, Lindberg s. n. (Lectotype: H!, designated by Väre (2012: 75)).

= Batrachium nevense Tzvelev (1998: 75)

= Ranunculus nevensis ( Tzvelev (1998: 75)) Luferov (2002: 34)

Type: RUSSIA, In aquis lente fluentibus ramulorum Newae fl. copiosissima, 23 June 1890, Meinshausen s. n. (Holotype: LE!, isotype: LE!).

— Batrachium floribundum auct., non ( Babington (1855: 397)) Dumortier (1863: 216): Tzvelev (1998: 74), p. max p.; Tzvelev & Grintal (2001: 169), p. max p.; Kravchenko (2007: 54); Tzvelev (2012: 147), p. max p.

— Batrachium langei auct., non Schultz ex Nyman (1878: 16): Kreczetovicz (1937: 350)

— Batrachium peltatum auct., non (Schrank) Petrovsky (1971: 180): Petrovsky (1971: 180)

— Batrachium penicillatum auct., non Dumortier (1863: 216): Tzvelev (1998: 74); Tzvelev & Grintal (2001: 170); Kravchenko (2007: 54); Tzvelev (2012: 147)

— Ranunculus peltatus auct., non Schrank (1789: 103): Cook (1964: 237), p. p.; Cook (1966: 113), p. p.

— Ranunculus peltatus subsp. peltatus auct., non Schrank (1789: 103): Cook (1993: 285), p. p.; Dahlgren & Jonsell (2001: 260), p. max p.

— Ranunculus rhipiphyllus auct., non Bastard ex Boreau (1857: 11): Ivanova (2001: 59), p. max p.

Morphological description of Ranunculus schmalhausenii

Vegetative shoots prostrate, 20–40(–50) cm long, with adventitious roots at almost every node; internodes 7–10, truncated, equal or shorter than opposed leaves; basal part prostrate with 3–5 internodes, terminal part erect with 5–7 internodes ( Fig. 8 ). Generative shoots erect, 100–200(–300) cm long, in the upper part almost dichotomously branched; internodes 6–7, from slightly to many times longer (in river forms sometimes slightly shorter) than opposed leaves ( Fig. 8 ). Floating leaves almost always present, the leaf lamina 15–30(–40) mm in diam., rounded to reniform, 5-lobed or -divided, with broadly cuneate lobes, margin acutely crenate or dentate, basal sinus 30–120° in lake forms, 90–180° in river forms; petiole 25–80(–150) mm long ( Fig. 5 , 6 ). Intermediate leaves rarely present, resembling floating leaves but with the lamina with some lobes divided into capillary segments as in submersed leaves, sometimes with only capillary appendages or some lobes with tips being extended into fine points (see figs. in Movergoz 2014). Submersed leaves with the lamina 10–100(–150) mm long, globose to obconical, up to 8(–10) times divided, with numerous (up to 200 or even more) terminal capillary segments; the segments divergent, lying in different planes, rigid or flaccid; petiole 5–80(–170) mm long. Stipules oblong to triangular, obtuse at apex, adnate to petiole for 3/4 or more of the length. Peduncles in fruit (30–)50–110(–210) mm long, longer than the opposed leaf, straight. Sepals 5, 3–6 mm long, spreading, caducous. Petals 5, sometimes 6–12, (5–) 7–17 mm long, broadly obovate, contiguous during anthesis; nectar-pits elongate pyriform, often in aggregation of 2–4 nectar-pits per petal. Stamens 15–30. Carpels 20–50(–65), 1.2–2.2 × 1.0– 1.7 mm, rounded to rounded-ovoid, unwinged, slightly hairy to glabrous; style lateral to subterminal. Receptacle globose, glabrous or slightly hairy. No signs of sterility was observed.

Diagnostic features: relatively long petioles and the first segments of the submerged leaves, the next segments are gradually shorter, with relatively short and numerous terminal segments which give brush-like appearance to the leaf laminas.

Chromosome number

Uotila & Pellinen (1985) provided the chromosome number 2n = ca. 32 for a plant gathered in south Finland and identified as Ranunculus peltatus . However, no voucher specimen exists, but R. peltatus does not occur in Finland at all (see below), and most probably this count refers to R. schmalhausenii . No other reliable chromosome number data is available for this species.

Distribution and habitat

Ranunculus schmalhausenii is endemic to North Europe ( Fig. 1 ) and mainly to Fennoscandia ( Norway, Sweden, Finland and North of European Russia, including Murmansk region, Republic of Karelia, adjacent north-western part of Leningrad region and westernmost part of Arkhangelsk region). It occurs in:

Russia: Arkhangelsk region (only along west border of the region), Leningrad region (north-western part), Murmansk region and Republic of Karelia. The nearest locality of R. peltatus (with which R. schmalhausenii had been mixed) in Russia is known in Kaliningrad region, also this species occurs in adjacent Estonia, Latvia and Lithuania.

Finland: All provinces, possibly except Åland, from where we have not seen specimens of R. schmalhausenii to date.

Sweden: Most of the provinces, except southern part of the country (provinces according to Jonsell 2004): Göteborg and Bohuslän, Inre Småland, Öland, Skåne, Uppland, Värmland, Västergötland were R. peltatus occurs.

Norway: Possibly most of the provinces, except southern part, but we have not seen enough herbarium materials to say it with certainty and provide list of particular provinces.

Estonia: Judging from the specimens collected in Russia near the border with Estonia R. schmalhausenii can be expected in northeastern part of the country. Some herbarium specimens examined from this area were similar to R. schmalhausenii but their bad quality prevented precise determination.

The major part of the distribution area of R. schmalhausenii is situated between 60° and 70° N and 5° and 38° E. This area was mostly covered by ice during the last Valdaian (Weichselian, Würmian) glaciation ( Jonsell 2004, Svendsen et al. 2004) and is represented by young postglacial landscapes of the Baltic Shield and partly of the Scandinavian Caledonides with age less than 10 000 years.

Ranunculus schmalhausenii prefers deep, clear and clean lakes, occurring abundantly in Fennoscandia. Data of habitat conditions of the species received in result of our own field observation in Murmansk region and Republic of Karelia were compiled in Table 6. Usually it grows at a depth of 1–3 m, sometimes forming low-density zones around water bodies at those depths. Plants are wave action resistant. Ranunculus schmalhausenii occurs on both soft and solid substrates: clay, pebbles, sand, stones, silt, but most frequently on mixture of sand and stones. It inhabits lakes where water temperature is low, even during the warmest period of the growing season and rarely exceeding 20°C. Sometimes R. schmalhausenii occurs also in rivers, especially those connecting with the lakes and forming the lake-river systems. In rivers its populations occupy deep reaches with depth of 1–2 m and weak flow up to 0.2 m /s, and shallow rapids and riffles with depth up to 1 m and current velocity up to 0.5 m /s, in both cases on stony ground. Judging from labels of herbarium specimens of plentiful collection of the species in H and according to P. Uotila (pers. comm.) in Finland R. schmalhausenii quite often occurs in rivers especially in the north and close to the sea. The very partitioned hilly-ridge and low-mountainous relief of Fennoscandia resulted in a dense lake and river system formed after the last Valdaian glaciation ( Jonsell 2004, Svendsen et al. 2004). The mainly siliceous bedrocks (gneisses, granites, porphyres, sandstones etc.) are underlying the Quaternary deposites or reaching the surface, and it is reflected in the chemical parameters of water. Water sampled from the localities of R. schmalhausenii had very low mineralization rate (8–48 ppm) and neutral pH (6.6–7.6). The water was transparent, with weak yellowish tinge (colority 20–80 degrees). The lakes and rivers inhabited by R. schmalhausenii were very clean (oligosaprobic), oxygen-rich (96–111 %), with very low or low content of organic matter (oligo- to mesotrophic). The species obviously avoid acidic brown waters. The presented data are well corresponding with description of habitat conditions in Kurimo (1970), Uotila (1971), Hämet-Ahti et al. (1998) and Dahlgren & Jonsell (2001). We realize that our original data concerns only limited part of R. schmalhausenii range but they could have general significance for the whole area because natural conditions in Fennoscandia are more or less similar.

It should be mentioned that in H we have seen some specimens similar to R. schmalhausenii from coastal bays in the northern part of the Gulf of Bothnia. Part of these plants belongs to the brackish water species R. baudotii , others to hybrids of R. schmalhausenii (see below), but for some of them further investigations are obviously required.

Shoot system and biology of Ranunculus schmalhausenii

Ranunculus schmalhausenii is an obligatory aquatic, long-lived perennial. Terrestrial forms were not evidenced. The species develops two types of shoots ( Fig. 6 , 8 , also see figs. in Movergoz 2014). Shoots of the first type are vegetative, prostrate in the basal part, and ascending to erect in the terminal part but normally not reaching the water surface. Almost every node has long adventitious roots. This kind of shoots bear only submersed, capillary leaves and are presented all year round forming dense mats on lake bottom. Shoots of the second type are generative, erect and reaching the water surface. They bear floating and submersed leaves, produce flowers and fruits. Evidently, a few shoots of the first type are transformed into the shoots of the second type due to a fast growing. The number of shoots of the second type is very small in comparison to the vegetative shoots of the first type (there is ca. one or even less generative shoot per square meter of a dense mat built out of the vegetative shoots). The upper part of the generative shoots are almost dichotomously branched with fistulose, buoyant internodes ( Fig. 8 ). Dense system of branches, floating leaves and flowers forms floating “rafts” ( Fig. 6 ). Generative shoots are present only for a short time during the growing season, in the time of flowering and fruiting. Normally this period is not longer than one month, sometimes spaning only two weeks, between the end of June and the end of July. Just after or even during fruiting, generative shoots start to detaching and can floating freely for a couple of days before the final decomposing. In spite of special searching we had not found germinating seeds or seedlings, but it is complex task considering very special habitats of R. schmalhausenii . Propagation by seeds seem to have minor role in comparison to the vegetative propagation which is much more effective especially in deep lakes and fast flowing rivers in the northern environments of Fennoscandia. The most similar shoot system and life strategy is expressed by R. fluitans ( Cook 1966) and some forms of R. penicillatus ( Cook 1966, Zander & Wiegleb 1987).

Communities of Ranunculus schmalhausenii

In contrast to many other species of Batrachium which are capable to form dense communities with significant cover and produce considerable biomass ( Cook 1966, Dawson 1976, Spink 1992, Hatton-Ellis & Grieve 2003, Bobrov & Movergoz 2014), R. schmalhausenii usually occurs in sparse stands or even as separate individuals and does not produce high amount of biomass. The biomass of R. schmalhausenii stands with the projective cover 50–80 % was 16–80 g /m 2 of the dry matter that is 3–10 times less than the biomass of other water crowfoots of comparable size ( Dawson 1976, Spink 1992, Bobrov & Movergoz 2014).

In the lakes studied ( Table 7) the communities of R. schmalhausenii occupied areas from few to tens and rarely to hundreds of square meters with the projective cover 20–80 % and with the distinct optimum in open water with wave action and sandy bottom. The water crowfoot formed stands with admixture of other macrophyte taxa. From vascular plants only Lobelia dortmanna , Myriophyllum alterniflorum , Ranunculus reptans and Sparganium gramineum were recorded from more than one relevé. Eleocharis acicularis , Isoёtes echinospora, Potamogeton alpinus and P. perfoliatus were registered only once, as well as moss Fontinalis antipyretica .

One community of R. schmalhausenii from river conditions was analyzed ( Table 7). It formed not large patch in flowing river stretch with pebbly bottom and with the projective cover 75 %. Similarly to lake communities it was also poor in species, there were only Fontinalis antipyretica , Myriophyllum alterniflorum and the river submersed form of Sparganium emersum .

In some places R. schmalhausenii occurred as single to few individuals and did not form specific communities. In such cases we recorded species occurred in the surrounding area ( Table 7). In such places the species composition was different. Besides Myriophyllum alterniflorum and Sparganium gramineum , in these localities Nuphar lutea , Nymphaea candida , Sparganium angustifolium , Utricularia intermedia and U. vulgaris were observed. These species, sensitive against wave effect, may compete successfully with R. schmalhausenii under the absence of wave action.

Similar communities as described above in the terms of the species composition and its ecological characteristic were given by Påhlsson (1994) as “ Myriophyllum alterniflorum – Ranunculus peltatus –typ” reported for Fennoscandia. Altogether 15 macrophyte species were recorded within communities or growing nearby R. schmalhausenii individuals. The species richness evidenced for the communities of R. schmalhausenii is similar or lower than in the other Batrachium communities ( Wiegleb & Herr 1985, Passarge 1992), and the species list is considerably different. The communities of R. schmalhausenii mainly contain oligotrophic lake species in contrast to mainly meso- or eutrophic species of wide ecological range characteristic for the other Batrachium associations ( Wiegleb & Herr 1985, Passarge 1992).

In spite of that presented original data concerns only limited part of R. schmalhausenii range they could have general significance for the whole area because natural conditions in Fennoscandia are quite similar and information about communities of the species are scanty and very scattered.

Hybridization

During our study of herbarium material we have found some extreme morphotypes of Ranunculus schmalhausenii , which based on the preliminary morphological study can represent interspecific hybrids. Brief account on these hybrids are provided below. Most of the specimens were marked as different hybrids already by previous researchers.

Ranunculus aquatilis × R. schmalhausenii . This putative hybrid is represented by only one herbarium specimen collected in Finland, Finland proper (Regio aboënsis) (Lindberg H 189860). It is a sterile plant with inflated shoots, short and dense submersed leaves (like R. schmalhausenii ) and 3–5-lobed (or -divided) floating leaves with a dentate margin (resembling R. aquatilis ). Flowers are of intermediate size and nectar-pits of an intermediate shape, receptacles are sparsely hairly. This specimen was collected in the area where both putative parents occur, judging from the general appearance of the plant it was gathered from a lake. In another determination there was Gelert’s label “ Batrachium paucistamineum × peltatum ”, which is close to our determination.

Ranunculus confervoides × R. schmalhausenii . This putative hybrid seems to be not rare since we have found specimens collected from five localities in Finland and three in Russia. Localities evidenced in Finland: South Karelia (Karelia australis) (Ulvinen H 805337), North Savo (Savonia borealis) (Roivainen H 801884, 801885), Central Ostrobothnia (Ostrobottnia media) (Fontell H 357391, Marklund H 357386, Särkkä & Palohuhta H 741081, Storbacka H 598567), Oulu Ostrobothnia (Ostrobottnia ouluensis) (Kiimalainen H 357408, 357421, Tolvanen H 357429, Ulvinen H 706093), Kuusamo Region (Regio kuusamoënsis) ( Askola H 483360), and in Russia: Republic of Karelia (Karelia olonetsensis) (Simming H 357398, 357519 and ex herb. Trautvetter LE s. n.), Leningrad region (Golubeva LE s. n.), Murmansk region (Bobrov & Sharapov IBIW s. n.). This partly fertile, putative hybrid combines features of both parents. Plants are of an intermediate size; floating leaves with the lamina from 3–5-lobed (or -divided) with dentate margin up to 5-lobed with entire margin, basal sinus from narrow to wide up to truncate or rotundate base; submersed leaves like in R. schmalhausenii but smaller and sparser (influence of R. confervoides ); flowers of intermediate size, nectar-pits of intermediate shape, receptacles with sparse hairs. Some plants resemble R. confervoides but develop small floating leaves, the others are similar to R. schmalhausenii but are slender and with only small and reduced floating leaves. The hybrid individuals were gathered from localities where both parents grew together or nearby each other, sometimes in transitional habitats between lakes and rivers, also in coastal bays of the Gulf of Bothnia and the Kandalaksha Gulf. On most of the specimens studied there were close determinations as “ Batrachium paucistamineum × peltatum ”, “ Ranunculus confervoides × peltatus ”, “ R. peltatus × trichophyllus ”.

Ranunculus schmalhausenii × R. trichophyllus s.l. (incl. R. kauffmannii Clerc (1878: 107)) . This putative hybrid was recorded from one locality in Finland, namely Kainuu (Ostrobottnia kajanensis) (Ohenoja H 695769, Ulvinen H 695770, 695771, 699658, 706100, Väisänen H 695774) and three localities in Russia: Republic of Karelia (Kravchenko IBIW s. n., PTZ s. n.), Leningrad region (Tzvelev 583 LE) and Vologda region (Bobrov et al. IBIW s. n., Bobrov & Sharapov IBIW s. n.). Individuals representing this morphotype are sterile and have an intermediate appearance between putative, parental species. Specimens are large, with inflated upper part of shoots (influence of R. schmalhausenii ), floating leaves rarely present with the lamina 3–5-lobed or -divided with crenate or dentate margin and very wide basal sinus; intermediate leaves often present, forming very gradual transition from submerged leaves to normal floating leaves; submerged leaves long but sparsely divided; flowers and nectar-pits of intermediate size and shape, receptacles with sparse to dense hairs. Individuals representing this putative hybrid occurred in the localities mostly without parental species or exceptionally with one of them, but within the range of both parents. This taxon evidently prefer rivers and usually grow in fast flowing stretches. Some specimens ascribe us to this hybrid were with close labels as “ Ranunculus confervoides × peltatus ”, “ R. peltatus × trichophyllus ”.

All these putative hybrids were mentioned for Fennoscandia before ( Hämet-Ahti et al. 1998, Dahlgren & Jonsell 2001) under other names (as hybrids of R. peltatus with R. aquatilis (including R. trichophyllus ) and R. confervoides ) without morphological descriptions, distribution and habitat information. Regarding that morphologically similar hybrids were reported from the other areas as hybrids of R. peltatus s.str. ( Stace 1975) further comprehensive revision of European Batrachium hybrids is desirable.

Key to the heterophyllous species of Ranunculus section Batrachium occurring in North Europe (Fennoscandia and in the adjacent areas)

1. Brackish water plants. Floating leaves frequently absent or weakly developed, usually present in shallow water forms; with the lamina 3(–5)-lobed or -divided, with cuneate lobes, leaf margin acutely crenate or dentate, basal sinus usually 90–180°, the lamina of floating leaves frequently with widely cuneate base. Flowers 15–20 mm in diam., nectar-pits lunate, single. Carpels winged. Through Europe ................................................................................................................................................................. R. baudotii

- Freshwater plants. Floating leaves almost always well-developed, especially on flowering shoots; with the lamina (3–)5(–7)-lobed or -divided, with broadly cuneate lobes, leaf margin acutely or obtusely crenate or dentate, basal sinus and the lamina base are similar or different. Flowers of the same size or larger, nectar-pits cup-shaped, circular, pyriform, single or in aggregation of 2–4 per petal. Carpels unwinged. Distribution range is mainly another...................................................................................................2

2. Submersed leaves (5–) 10–30 cm long, equal to or longer than the corresponding internodes, more or less flaccid, collapsed when taken out of water, with terminal segments more than 1 cm long. Flowing water plants..................................................................3

- Submersed leaves 2–8(10) cm long, shorter than or almost equal to the corresponding internodes, more or less rigid, not collapsed when taken out of water, with terminal segments less than 1 cm long. Still water plants.................................................................4

3. Receptacle glabrous or slightly hairy. Flowers 15–35 mm in diam., petals 5, sometimes 6–12, nectar-pits pyriform, often in aggregation of 2–4 per petal. Floating leaves always present, the lamina 5-lobed or -divided, leaf margin acutely crenate or dentate, basal sinus usually 90–180°. Intermediate leaves rarely present, the lamina with some lobes entire and some divided into capillary segments like in submersed leaves, sometimes with only capillary appendages or some lobes with tips being extended into fine points. Submersed leaves with long petioles and long first segments of the lamina, with segments of next divisions becoming gradually shorter, with relatively short terminal segments. Fennoscandia ........................................ R. schmalhausenii (river form)

- Receptacle densely hairy. Flowers 20–30(–40) mm in diam., petals 5, rarely 7, nectar-pits pyriform or trasitional to cup-shaped, single. Floating leaves sometimes present, the lamina 3–5-lobed or -divided, leaf margin acutely crenate or dentate, basal sinus usually 120–180°. Intermediate leaves frequently present, the lamina with some lobes entire and some divided into capillary segments like in submersed leaves, frequently with capillary appendages or some lobes with tips being extended into fine points. Submersed leaves with short petioles and more or less equal segments of all divisions of the lamina. Central and Western Europe ....................................................................................................................................................................................... R. penicillatus

4. Receptacle glabrous or slightly hairy. Submersed leaves with the lamina 5–8(–10) times divided, with up to 200 or more terminal capillary segments. Petals 5, sometimes 6–12, nectar-pits often in aggregation of 2–4 per petal. Floating leaves with the lamina 5-lobed or -divided, leaf margin acutely crenate or dentate, basal sinus usually 30–120°. Intermediate leaves rarely present, the lamina with some lobes entire and some divided into segments like in submersed leaves, sometimes with only capillary appendages or some lobes with tips being extended into fine points. Flowers 15–35 mm in diam., nectar-pits pyriform. Fennoscandia ..... ............................................................................................................................................................. R. schmalhausenii (lake form)

- Receptacle densely hairy. Submersed leaves with the lamina 3–5(–6) times divided, with up to 100 terminal capillary segments. Petals always 5, nectar-pits single. Floating and intermediate leaves have different characters, size of flowers and shape of nectar-pits are similar or different, distribution range is mainly another......................................................................................................5

5. Floating leaves well-developed, distinctly differentiated from submersed leaves; the lamina (3–)5(–7)-lobed, leaf margin obtusely crenate, basal sinus usually 30–120°. Flowers 20–30(–40) mm in diam., nectar-pits pyriform. Peduncles longer than the opposite floating leaf. Flowering plants always heterophyllous. Central and Western Europe, in Fennoscandia only in southernmost provinces of Sweden................................................................................................................................................................... R. peltatus

- Floating leaves frequently underdeveloped, with gradually transition from capillary submersed to lobed floating leaves; the lamina (3–)5(–7)-lobed or -divided, leaf margin dentate, basal sinus usually 0–90°. Flowers 10–20 mm in diam., nectar-pits cup-shaped or circular. Peduncles shorter or equal than the opposite leaf. Flowering plants homophyllous or heterophyllous. Through Central and Western Europe, in Fennoscandia only in southernmost provinces of Norway, Sweden and Finland, in western part of Leningrad region and south-west of Republic of Karelia in Russia................................................................................................... R. aquatilis

Figures

FIGURE 1. Geographical range of Ranunculus schmalhausenii (outlined) with the localities of field investigation and DNA sampling in Finland and North-West of European Russia (dots). Dash line shows preliminary range border due to insufficient data.

FIGURE 5. Herbarium specimens (H) of Ranunculus schmalhausenii of different morphotypes: A—typical lake form (Russia, Murmansk region, lake Notozero, H 801405), B—typical river form (Finland, Kittilä Lapland, Ylikylä, H 801383), C—form with lobed petals (Finland, Finland proper, Jalassaari, H 801409), D—form with many petaled flowers (Finland, South Häme, lake Norijärvi, H 043172).

FIGURE 6. Ranunculus schmalhausenii in the wild in Republic of Karelia, Russia:A—plant in deep water of lake Srednee Kuito (vicinity of town Kalevala), B—whole plant in the shallow of lake Bolshoe Severnoe (vicinity of village Sosnovyi),C, D—floating upper vegetativegenerative part in the shallow of lake Bolshoe Severnoe (vicinity of village Sosnovyi). Photos A.A. Bobrov, (A) 16 July 2012, (B–D) 17 July 2012.

FIGURE 8. Individual plant of Ranunculus schmalhausenii (Russia, Republic of Karelia, lake Verknyaya Kuzemka, IBIW) with different types of shoots:A—vegetative, prostrate shoots, B—lower part of generative shoot, C—upper part of generative shoot.