Eriocaulon megapotamicum Malme

Eriocaulon megapotamicum is much larger than E. modestum. The leaves are up to 50 cm long, more or less erect and up to 10 cm wide. The peduncles may reach about 1 m in length. The phyllotaxis changes from distichous in the vegetative phase to spiral in the reproductive phase. Renewals are again distichous. However, this change in phyllotaxis is difficult to see in herbarium specimens as vegetative material is rarely collected. Very weak plants may form their single capitulum without changing to the spiral phyllotaxis, and this facilitates the analysis of such plants.

Generally the position of the sheath apex can be detected easily in the transverse section as the sheath is thicker in the median part. If not, the orientation can be seen from the oblique truncation of the sheath apex. Leaf no. 4 (Fig. ​(Fig.1j,1j, dotted) is the pherophyll of an axillary shoot with two leaves (bright grey). The phyllotactic pattern would also allow the first leaf of the lateral shoot to be regarded as leaf no. 5 of the main shoot. In this case, the position of the sheath would, however, be inverse to what would be expected according to phyllotactic rules. The prophyll has to be with its dorsal side towards the main axis, and this is only the case if the interpretation given here is adopted. In monocot inflorescences, the adorsed position of the prophyll may also be slightly dislocated to a more lateral position, but it is never shifted to the abaxial side.

In Fig. 1K, L the pattern is basically the same. A slight shift towards a spiral phyllotaxis can be seen, and the first-order lateral axis is also terminated by a capitulum with a sheath. The second leaf of the first-order lateral axis (dotted) serves as a pherophyll for a second-order lateral axis represented only by the nearly adorsed prophyll. The most important difference between Fig. 1N and L is that the prophyll of the first-order lateral axis serves directly as the pherophyll of a second-order lateral axis.

In Fig. 1F–H, a much more complicated individual and the analysis of the ramification pattern are shown in a longitudinal (Fig. 1F) and transversal scheme (Fig. 1H) and a photograph of a transversal section of the rosette (Fig. 1G). A total of 18 capitula are arranged in six groups of 1–5 capitula. There is an obvious difference in age between the different groups, which can be detected from the diameter of the peduncles, the length of the peduncles, the diameter and flowering sequence of the capitula, and – to some extent – from the colour of the leaves. As the leaf growth is exclusively basiblast, younger leaves are cut nearer to the apex than older ones and thus appear more intensely yellowish green. The most obvious indicator is, however, the relative position within the rosette. Leaf nos 1–4 are obviously inserted on the main axis. Leaf no. 3 and no. 4 serve as pherophylls for first-order lateral shoots. The main shoot is terminated by a group of four capitula, of which the one in the middle of the rosette has the longest peduncle and therefore seems to be the one terminating the main axis. There are, however, no pherophylls for the other capitula. The position of the sheath is not detectable on the transverse section as the rather wide sheaths are folded irregularly due to lack of space, and the thickness of the sheath is about the same along the entire circumference (in contrast to the small individuals shown in Fig. 1I–N). On the intact plant, the sheaths appear to be positioned towards the centre of the group instead of towards the periphery of the rosette, indicating that the sheaths are the prophylls of the peduncles. The same pattern is repeated in both first-order lateral shoots. The lateral shoot on the left is terminated by a group of five, the one on the right by a group of four peduncles, each peduncle with a surrounding sheath. Again, in the axils of the two uppermost non-sheathing vegetative leaves, continuations are placed on either side (Fig. 1F, marked with asterisks), each starting with a rather perfectly adorsed prophyll. Three of these four shoots terminate in a group of two or in a single capitulum; the fourth seems to be still vegetative.

It is important to note that all capitula of the plant illustrated in Fig. 1F–H are flowering in the same season. The analysis was performed in December; the flowering period may extend from late October to February. Within this period, the pattern described above may be repeated several times. After the end of the flowering period during winter (March to September), continuations in similar positions produce a much larger number of leaves in clearly distichous order. It has to be noted that even the plant in Fig. 1F–H is a smaller one, indicated by the distichous arrangement of the vegetative leaves. Larger individuals shift to an alternate phyllotaxis before they develop inflorescences and produce far more peduncles (Fig. 1O, P). In such individuals, it is much more difficult to analyse the ramification pattern.

Syngonanthus caulescens (Bong.) Ruhl.

Syngonanthus caulescens is a widespread and highly variable species. At high altitudes in mountain areas, on poor soils and freely exposed, the species may have an acaulescent habit with only few capitula. Under favourable conditions, however, it develops the typical umbellate habit (Fig. 2D). In younger stages it can be seen that the development also starts from the top of the inflorescence and proceeds in basipetal sequence (Fig. 5E). The central capitulum is the oldest one. It seems to be the first to be formed in the sequence of capitula and it is the first to start blooming. The other capitula all have their sheath in an adaxial position, which indicates that the sheath is the prophyll of the lateral capitula in a composed inflorescence that is terminated by a sheathed peduncle with its capitulum. Further capitula may be formed in a basipetal sequence (Fig. 2F). However, in inflorescences, there is no fixed number of elements similar to most flowers. Therefore, Fig. 2E cannot be regarded as a younger stage of Fig, ​Fig,2F.2F. Both may have different numbers of capitula ab initio. The structure is thus essentially the same as for the groups of capitula in E. megapotamicum. However, the number of capitula is significantly higher than in this species. The spiral arrangement of the lateral capitula is best indicated by the arrangement in clockwise and counterclockwise parasticha.

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Fig. 2.

(A and B) Paepalanthus erectifolius. (A) Habit; most parts of the basal rosette are already rotten when the plant is flowering. (B) The umbel-shaped stand of capitula is composed of several units in the axils of well-developed pherophylls; the units are formed in a basipetal sequence; within these units, pherophylls are lacking. (C) Syngonanthus chrysanthus. The cushion-like groups of rosettes may originate from different seeds, but can also be lateral branches emerging from the lower side of a rosette of the previous year; a rosette may bear a single or up to about 150 capitula. (D–F) Syngonanthus caulescens. (D) A caulescent stem carrying an umbel of capitula. (E) Young stage of a stand of capitula; the arrangement in parasticha can be seen; pherophylls for the individual capitula (including their sheath) are lacking; the adorsed position of the sheath indicates that it represents the prophyll. (F) Slightly older stage of a similar inflorescence.

After anthesis at about seed ripening of the terminal unit, in the axils of the uppermost leaves lateral inflorescences of the same structure may be formed, which may be preceded by one to several leaves and even folious stems. If fruiting erect stems of S. caulescens are washed down, lateral inflorescences may be formed in the axil of any leaf of the stem. In herbarium specimens this is difficult to be seen, but it is indicated frequently by the lateral inflorescences all being directed to one side. Usually, S. caulescens seems to be annual or at least short-lived. Under favourable conditions, iterations (renewals) may occur from the base of the caulescent stems after seed dispersal and usually after all or most parts of the terminal umbel have dried back. However, it may be difficult to distinguish basal renewals from plantlets originating from different seeds even in the field. In herbarium specimens, this is mostly impossible.

Syngonanthus chrysanthus (Bong.) Ruhland

Syngonanthus chrysanthus has an inflorescence structure that is very similar to that of S. caulescens, but never develops an elongated stem (Fig. 2C). Weak plants have a rosette diameter of <3 cm and only a single capitulum. In strong plants, the rosette diameter may be up to 20 cm and the number of capitula may exceed 150, all forming a single botryoid of capitula. In many places, the species appears to be hapaxanth. Under favourable conditions, one or several renewals may be formed at the base of the rosette. If there is only one renewal, the peduncles persisting sometimes for several months on the plant are all shifted to one side of the new rosette. If several renewals are formed, this may lead to a circular arrangement of the new rosettes. The remains of the previous rosette in the centre may still be present or can disintegrate completely before the lateral rosettes start flowering. Theoretically this growth mode may leads to cushion-like arrangements of inflorescences, and under greenhouse conditions this in fact happens. In the field, cushions seem to be rare in this species, but circular or garland-like arrangements of daughter rosettes of one individual have been observed.

Paepalanthus erectifolius Silveira

The inflorescence of P. erectifolius looks umbel-like; it is, however, composed of several units of the type described for S. caulescens as the terminal unit (Fig. 2A, B). One of these units terminates the long caulescent stem; the others are placed in the axils of several bracts directly preceding the terminal unit. As in S. caulescens, within all these units no pherophylls for the individual peduncles are formed. One of the peduncles in the centre of each unit is longer than the others, and this one is thought to terminate the unit; developmental studies in this species are, however, lacking. The plant growth starts with a rosette of relatively long leaves. When the inflorescence formation starts, the rosette leaves dry back, and they are usually rotten when the plant is finally at anthesis. The leaves on the erect stem are much smaller than the rosette leaves (only half to one-third of the length of the rosette leaves). Rosette leaves are usually lacking on herbarium specimens, and it is unclear how long the process from germination to blooming takes. Generally there seems to be no renewal from the base or from the inflorescence; the species is hapaxanth.

In case the developing inflorescence is damaged or removed, e.g. due to pasture, several lateral inflorescences are formed, each repeating the pattern of the original terminal inflorescence. Such plants are smaller and have many more capitula than undamaged plants. As they tend to fit better on a herbarium sheath, they are found frequently as herbarium specimens.

Actinocephalus polyanthus (Bong.) Sano

The inflorescences of this species are composed of up to about 20 lateral branches formed in a series of consecutive leaves on a stem up to about 1 m high (Fig. 3A, B). The elongate stem arises from the centre of a big rosette which seems to grow vegetatively for several years until it finally changes to the flowering stage by producing an elongate flowering stem from the apical meristem of the rosette. Each of the lateral branches terminates in an umbel of >100 capitula, each of them bearing about 100–150 flowers. The main axis remains sterile; the species is hapaxanth and dies after flowering. The initiation of the lateral flowering units starts from the rosette prior to the elongation of the main axis. This leads to concaulescent shifts of the lateral branches nearly up to the lower side of the next leaf. During the intercalary growth, the pherophylls of lateral umbel-like groups of capitula are often ruptured longitudinally because of their oblique insertion.

Actinocephalus bongardii (A. St.-Hil.) Sano

Like A. polyanthus, the species forms a large plurienne rosette (Fig. 4A, B). The shift to the reproductive phase seems to take much longer than in the previous species, and at anthesis the basal rosette is usually no longer present. The rosette is therefore lacking in herbarium specimens and is also not mentioned in the original description of the species. The number of the lateral units terminated with umbel-like stands of capitula is only 3–5, and thus generally much lower than in A. polyanthus. As metatopies are lacking, the intercalary growth seems to be largely finished when the flowering lateral braches are formed. In contrast to A. polyanthus, the main axis of the plant generally goes on growing vegetatively for a longer period. After a while (it is unknown whether this is a year or only another wet season of the same year), a second group of lateral umbels may be formed. Each group of umbels arises from consecutive leaves on the erect stem. Subsequent groups are separated from each other by a larger number (20 up to >50) of sterile leaves. Up to three groups of umbels representing different flowering periods have been reported before the plants finally seem to die.

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Fig. 4.

(A–D) Actinocephalus bongardii. (A) T. Stützel with a plant at anthesis, the basal rosette has deteriorated as in P. erectifolius; umbel-like units are formed laterally to the main axis. In contrast to P. polyanthus, after a phase of vegetative growth, a set of new lateral units can be formed. (B) Longitudinal scheme. (C and D) Development of the umbel-shaped units, (C) without and (D) with annotation of the subunits and sequence of formation within the terminal unit. (E) Actinocephalus robustus forms a monopodial erect rosette growing for many years; umbel-shaped lateral inflorescences are formed in the leaf axils of 5–10 subsequent leaves. The species lacks vegetative branching (photo: Livia Echternacht).

For A. bongardii it was possible to analyse the ramification pattern within the umbel-like arrangements. The primordia in Fig. 4C, D will form entire capitula including the sheath. Young umbels show a terminal unit representing a botryoid of capitula with one terminal capitulum (marked) and several lateral capitula in a basipetal (centrifugal) sequence. The terminal unit is surrounded by several similar units; two of them are marked in Fig. 4D. The lateral units are, however, deformed due to the limited space, so that the formation pattern is difficult to detect. The ‘umbel’ in A. bongardii thus represents the same structure as the entire terminal inflorescence in P. erectifolius.

Other species of Actinocephalus

In Actinocephalus robustus (Silveira) Sano (Fig. 4E) and A. brachypus (Bong.) Sano there is no distinction between a basal (or juvenile) rosette and an elongated stem at flowering, but the rosette seems to proliferate for a long time and forms lateral umbel-shaped inflorescences for many years. The rosette shows no basal renewals, and a little monopodial trunk is formed until the plant dies after an unknown number of years. In Actinocephalus falcifolius (Koern.) Sano, a creeping rhizome is formed bearing a terminal rosette of relatively small leaves (about 5 cm long and 5 mm wide). Reproductive shoots are in the axils of the rosette leaves. Each reproductive shoot is indeterminate and bears lateral umbels of capitula. These umbels are formed in acropetal sequence. Paepalantus falcifolius is the only species for which this pattern is known as yet.

Paepalanthus sect. Aphorocaulon Ruhl

Paepalantus incanus Koern. (Fig. 5B) looks at first sight similar to a minute Actinocephalus robustus. The lateral branches originating from the rosette form only a single botryoid of capitula. The number of capitula is small, and the peduncles are rather long so that an obconical shape of the lateral units results. Because of limited material of this rare species, it is not yet clear if the rosettes can branch vegetatively or if the group of rosettes in Fig. 5B represents several individuals.

Paepalanthus polygonus Ruhl. and Paepalanthus eriophaeus Ruhl

Paepalanthus polygonus is outstanding in the family because of its arborescent habit (Fig. 6A). The leaves on the vegetative vertical main axis are about twice as big as those on the flowering lateral branches. The lateral braches seem to branch dichotomously, but there are sometimes also trifurcations, which indicates that the branching is generally axillary. Paepalanthus eriophaeus (Fig. 6B) lacks a sterile main shoot and shows a branching rosette without elongated stem. In this way, cushions of a few to several rosettes are formed. Both species are characterized by a series of peduncles inserted together in the axil of the same pherophyll (Fig. 6C). Each peduncle is supplied with its own closed sheath, and a series of about 20 of such fertile leaves is formed in acropetal sequence each flowering season. Both species are obviously perennial. Fertile and sterile leaves are identical in size and shape. The remains of many flowering periods as well as traits of fires indicate that the species is long-living. The densely packed leaf bases on the stem seem to serve for fire protection and do not get burned.

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Fig. 6.

Branching patterns in closely related groups of Paepalanthus. (A) Paepalanthus polygonus has a unique arborescent habit. (B) Paepalanthus eriophaeus forms cushions of from three to more than six rosettes; in this specimen at the time of anthesis of one flush of capitula, a distinct second, still budding flush appears more apically. (C) Paepalanthus polygonus and P. eriophaeus are linked by forming groups of collateral capitula in the axils of 15–50 subsequent leaves. (D and E) Paepalanthus subgen. Platycaulon. (D) Sect. Conferti has globose arrangements of sessile capitula on a long cylindrical or slightly flattened peduncle with a basal sheath. (E) In sect. Divisi, all capitula are arranged in one plane; the individual capitula have a distinct short peduncle. The fused part of the peduncle is flat; a sheath at the base may be present or lacking. (F–I) Paepalanthus pruinosus. Development of inflorescences. (F) First the sheath surrounding the entire group of capitula is formed. (G) Slightly later, the primordia of the individual capitula become visible simultaneously. (H) One capitulum seems to be terminal to the entire group. (H and I) The first leaf of each capitulum takes the position of the pherophyll; the second is adorsed to the centre and takes the position which is held by the sheath in E. megapotamicum or S. caulescens. (J–L) Hypothetical transition from a botryoid of capitula to the Platycaulon inflorescence [redrawn after Stützel (1984)]; the prophyll of the entire unit in (E) forms a new sheat; pherophylls and sheaths of the individual capitula become part of the involucrum of the individual capitula; this interpretation is replaced here by a fragmentation of an oversized single capitulum.

Paepalanthus subgen. Platycaulon

Paepalanthus subgen. Platycaulon is characterized by composed capitula in the axils of the leaves of a proliferating rosette. The individual capitula may have a short stalk and are then all in one transverse plane (P. sect. Divisi Koern., Fig. 6E), or the individual capitula are sessile on a joint scape and form a semi-globous to nearly globous arrangement of capitula (P. sect. Conferti Koern., Fig. 6D). For the latter group, the ontogeny has been studied in P. pruinosus Ruhl. (Fig. 6F–I). The formation of the composed capitulum in this group starts from a very large primordium that first forms the transverse truncate sheath (Fig. 6F). The formation of the individual capitula is more or less synchronous (Fig. 6G), and the first leaf to be formed on each of them turns to the periphery of the entire group, and the second to the centre (Fig. 6H, I). Regarding its position, the first leaf corresponds to the pherophyll, and the second one to the prophyll of the individual capitulum. It has to be stressed that the individual capitula lack a pherophyll in most inflorescences of Eriocaulaceae described here, but that it is present in this group. In many species of P. subgen. Platycaulon, there is no vegetative innovation from the rosette. If there is one – as in P. costaricensis Moldenke ex Standl. – it arises from the lower side of the rosette, leading to a cushion-like arrangement of rosettes.

Paepalanthus catharinae Ruhl. and Paepalanthus caldensis Malme

Both species show the same pattern of branching and inflorescence formation. The capitula are solitary in the axils of normal rosette leaves (Fig. 1D, E). During the flowering season, they are formed in a series of consecutive leaves; the closed sheath is always in the adaxial position and represents the prophyll of the pedunculate capitulum. In the axil of those leaves that have not formed capitula after the flowering season, one to several vegetative branches may arise at the lower side of the rosette. This leads to cushion-like groups or flat mats of rosettes.

The Troll approach and the approach used here

In addition to floral morphology, the morphology of inflorescences has always been used in plant taxonomy. As there is much more intraspecific variability in the structure of inflorescences than in that of flowers, inflorescence morphology always appeared more complex and less uniform than floral morphology. Earlier attempts are summarized in Eichler (1875) and in Weberling (1989). The most comprehensive treatment of inflorescences is still that by Troll (1964, 1969), Weberling (1981, 1989), Troll and Weberling (1989) and Weberling and Troll (1998). The number of terms introduced by Troll to describe inflorescences grew continuously without making the approach more powerful in plant taxonomy. This is partly because the Troll morphology was intended to be diagnostic in establishing distinct types rather than being used for describing continuous evolutionary processes (Kunze, 1989). Later additions in theory and terminology appear to be partly a kind of ‘repair’ of weaknesses of the earlier concept.

Troll clearly has outstanding merits in making inflorescence morphology more precise and more useful in taxonomy. It is obvious that he started his work analysing annual plants. By doing so, he could base his comparisons on entire plants and did not have to select parts. This is the easiest way to avoid comparisons being based on non-homologous parts. When proceeding to perennial plants, he decided to use the annual growth unit (‘Jahrestrieb’) as the basis for comparisons. In the meantime, it has been demonstrated that this may lead to problems even in Europe when comparing taxa with species that moved from a Mediterranean climate with a winter vegetation period and draught rest in summer to the northern temperate zone with summer vegetation and cold rest in winter (Werner and Ebel, 1994). Briggs and Johnson (1979) have therefore replaced the annual growth unit by the seasonal growth unit (SGU). This works nicely in regions with clearly distinct seasons and for taxa that did not shift between regions with different climatic regimes or seasons during their evolution. The modified Briggs and Johnson approach is thus also only of limited use in regions with highly variable climatic conditions where two or more growing seasons may be incompletely separated by dry or/and cold phases. Our approach demonstrates that inflorescence morphology can be used as a powerful tool even if it is not possible to delimit clear SGUs.

Endress (2010) has clarified much of the previous terminological confusion. He already stated that the Troll terminology and some of the later refinements appear oversophisticated and sometimes hinder a clear understanding rather than help towards it. Our approach is therefore intended to be as clear as possible with as few terms as possible. We search for distinct and repetitive units on different levels of complexity. For each level we describe the kind of units formed (flowers, inflorescences of first, second, third …. order), the branching pattern within the unit and the sequence of formation of the respective units (Fig. 9). In Fig. 9 only hapaxanth species are represented, and the position and time lag between subsequent growth units are therefore lacking. However, it is possible to include that also in graphic representations. The given examples show that the level of complexity or aggregation and the formation sequence are independent features. The examples presented here demonstrate that the (repeated) combination of both features leads to a relatively simple description of highly complex inflorescences.

The patterns described in this way have been shown also to be relevant to detect evolutionary patterns. The delimitation of the synflorescence seems to be problematic even for comparisons within Eriocaulaceae. Therefore, we do not see a significant advantage of the synflorescence concept compared with the traditional inflorescence and abandon the term. Instead we try to identify larger time lags in the development of the flowering parts. For species for which only a few and isolated records are available (e.g. P. distichophyllus), data in this respect remain scarce. The parts formed between such vegetative lag phases may be distinct SGUs as defined by Briggs and Johnson (1979), but for many Eriocaulaceae this is not yet clear at all.

Troll (1964, 1969) stressed that two types – monotelic and polytelic – should be kinds of primary types, not linked at all; however as pointed out by Endress (2010), this concept is in conflict with an evolutionary approach to inflorescences. Sell (1969) has described an evolutionary pathway leading from monotelic to polytelic inflorescences by racemization and truncation.

He had already recognized that similar processes may be repeated on higher levels of complexity. His ‘double truncation’ is a kind of first step towards the secondary polytely as proposed by Kunze (1989). Sensu Troll, Eriocaulaceae are strictly polytelic as the first-order inflorescences (capitula) are always racemes (or racemous capitula) and thus indeterminate. However, on the seceond level of complexity we can find determinate units (e.g. S. caulescens) as well as indeterminate ones (e.g. P. catharinae). For these second-level inflorescences Troll used the term pseudoflorescences, with the paracladia terminating in pseudoflorescences he called long-paracladia (in contrast to the normal short-paracladia). The botryoid of capitula as described for E. megapotamicum and S. caulescens would represent such long-paracladia or pseudoflorescences. This strategy works for a second level of complexity. As shown, for Eriocaulaceae five levels of complexity would be needed. The same applies for grasses and many other taxa and, following the Troll strategy, further terms would be needed for units of higher complexity. However, it seems to be easier and clearer to number the levels of complexity consecutively and to describe the ramification pattern and formation sequence separately for each of them.

If there is a terminal unit for a given level of complexity, it is flowering earlier than the preceding ones. However, if there is no such terminal unit, initiation as well as the flowering sequence of these units is strictly acropetal. The pattern described as monotelic and polytelic by Troll (1964, 1969) for flowers is thus repeated on higher levels of complexity (capitula, racemes, thyrses or cyathia) in the same way. Schröder (1987) as well as Kunze (1989) have already pointed out the importance of such repetitive units on different complexity levels, and Schröder (1987) has even termed them ‘modules’. Rua (1996) and Pensiero and Vegetti (2011) faced similar difficulties when treating grass inflorescences. They dealt with grasses as if the spikelets were flowers. Otherwise they treated Setaria and Paspalum in the tradition of the Troll school without defining a hierarchical set of ‘modules’ or ‘units’. The similarities of patterns for second-order inflorescences described here for S. caulescens, A. erectifolius and others to the pattern described for Bruniaceae, especially Linconia alopecuroides (Claßen-Bockhoff, 200; p. 104), is striking despite the difference in the first-order inflorescences. This also underlines that it makes sense to analyse the complexity levels separately.

The double truncation as described by Sell (1969) and Kunze (1989) seems to be understood by both as two subsequent steps of loss. The fragmentation process as described for Paepalanthus subgen. Platycaulon suggests that there was never a complex terminal unit being lost in several steps. Instead, there was a step towards a higher complexity of the lateral branches. For a merely typological comparison in the Troll tradition, this would not make a difference. For an understanding of the evolutionary radiation, it is, however, essential.

Troll did not analyse meristem sizes, and the treatment of Bruniaceae by Claßen-Bockhoff (2000) is predominantly based on herbarium material and field work, and therefore also lacks studies of meristem sizes. Kunze (1989) used SEM studies only to detect the relative position of parts within an inflorescence. In the present study, the SEM technique was used also in the classical context, but the results showed that there are significant differences in size correlations. A comparative study of meristem properties for vegetative and inflorescence meristems should be undertaken for units of different complexity to achieve a better understanding of inflorescence evolution.

There is another interesting logical break in the terminology of the Troll school (and precursors). They define compound inflorescences ‘if the individual flowers of simple inflorescences (raceme, spike, umbel, and capitulum) are replaced by a complete inflorescence of the same branching type, then certain types of compound inflorescences, the double raceme [diplobotryum …], double spike, double umbel (…), and the double capitulum are obtained’ (Weberling, 1989; p. 207) (the German text from 1981 uses the term ‘dibotryum’ instead of ‘diplobotryum’). However, the dithyrse is not a thyrse in which the flowers are replaced by entire thyrses, but a raceme or botryoid in which all flowers are replaced by a thyrse (Weberling, 1989; p. 216). The description of the simple branching pattern is obscured by the introduction of further and unnecessary terms such as ‘Spezialthyrsus’ (erroneously translated as ‘sub-thyrse’ in Weberling, 1989). Weberling shows in his illustration of a pleiothyrse that the units appearing as compact and thus distinct sub-units may represent different levels of complexity. In his illustration (Weberling, 1989; p. 217) the sub-units of the entire inflorescence being distinct in habit or appearance are already dithyrses. In our way of describing inflorescences, this would correspond to an inflorescence of the fourth order, the first-order unit representing a cyme, and the second- to fourth-order units all showing the pattern of a raceme.

Troll already realized that the condensation to visually distinct units may occur on different levels of complexity. For this aspect, Troll used the terms ‘heterocladic’ and ‘disjunct heterocladic’. However, it is possible to describe these facts without introducing any new term. The occurrence of habitually distinct units allows a morphologically precise (typological) description for the arrangement of those units to be mixed a with a merely superficial description of the pattern within these units. Especially in floristics, key-making and related fields this can be a meaningful approach, whereas evolutionary studies as well as developmental genetics would require a precise (typological) approach throughout. If typological and descriptive approaches are mixed, it is important to indicate clearly which parts are understood throughout and for which parts only gross morphology is described. A comparison, e.g. within Actinocephalus, does not require a full understanding of the branching pattern within the ball-shaped umbels of capitula, but a comparison within the entire family does.

The present work is based mainly on fieldwork which would not have been possible without the support of many people. First studies were carried out during a joint field trip of T.S. to Serra do Cipo guided by Ana Maria Giulietti as early as 1987. Additional data were collected on field trips by M.T. together with Livia Echternacht (who also supplied photos and morphological information from her own field trips), T.S. together with Alessandra Ike-Coan and Aline Oriani, and all of them together. We are grateful for financial support to T.S. from the DFG and the Humboldt foundation, and to M.T. from FAPERJ, CAPES and the Humboldt foundation. Without the slight but continuous pressure by R. Claßen-Bockhoff on T.S., the manuscript would probably never have been finished. Major reorganization of a previous version of the manuscript would not have been possible without the help of N. Balnis and S. Adler. Last but not least we are grateful to Simon Mayo for liguistic adjustments and for many comments and fruitful discussions.