Pollen morphologicalevidence for

subdivision and affinities of

Jan Muller

Rijksherbarium, Leiden

Summary

A in is of demarcation subdivision ofthe pollen types encountered Lecythidaceae proposed. The presence a and line between an original colpate a derived syncolpate pollen type is confirmed. The significance of pollen characters for taxonomic subdivision is evaluated and it is concluded that the subdivision proposed

in by Niedenzu 1892 agrees best with the pollen evidence. Pollen morphology does not yet provide any

clear indications of wider affinities of the family, except in a negative sense.

Introduction

of In his monograph the genus Barringtonia (Lecythidaceae), Payens (1967) stated, after

reviewing the various proposals for subdivision by former authors, that 'a satisfactory be taxonomie subdivision of the family is still wanting and may not even possible'.

Although some of these authors, notably Niedenzu (1892) and Pichon (1945), paid

attention to pollen morphology, it was Erdtman (1952) who first pointed out that a line the characterized the clear demarcation runs through family, one part being by

syntricolpate Planchonia pollen type, the other by the tricolpate Lecythis type. This Melchior who based his evidence was not taken into account by (1964), subdivision of

the family on Pichon (194s). this character In the following it will be attempted to evaluate the significance of for

taxonomicsubdivision in Lecythidaceae and in addition to comment briefly on the wider

affinities of this family as far as these can be deduced from pollen morphology.

This note is dedicated to Professor Van Steenis on the occasion of his retirement and in

grateful recognition of his promotion of palynological studies at the Rijksherbarium.

POLLEN TYPES

of the of A preliminary account pollen morphology the genus Barringtonia was already

published in Payen's monograph (I.e., p. 169—171). Since then I have been able to of the extend my observations by studying the pollen all species of related genera Careya,

Chydenanthus, Combretodendron, and Planchonia. Their pollen proved to be basically that be included Planchonia similar to ofBarringtonia and can in a main type although the

variability within this type is considerably larger than suggested by Erdtman (1952). the A detailed account of this variability will form subject of a later paper.

of the of as far as available, was In addition, the pollen remaining genera Lecythidaceae, all the cursorily examined, proving to belong to the Lecythis main type. In following

scheme for which the subdivision of Niedenzu (1892) is adopted (table 1), a slightly

1 revised subdivision of the pollen types in Lecythidaceae is presented ).

The in 'A. *) opportunity is taken here to correct a most unfortunate error Payens, I.e., p. 170: Calyp- trocalyx main type' should read ‘A. Calyptrata main type'.

351 VOL. 352 BLUMEA XX, No. 2, 1972

of species 'folia neocaledonica calyptrata lougilongifolia papehpapch procera remaining Barringtonia Careya Chydenanthus CombretodendronCombretodendron Planchonia B. B. B. B. B.

type groove) typetype groove)groove) calyptrata asiatica marginal marginal

Barringtonia (without Barringtonia (with I Asteranthus Crateranthus NapoleoneaNapoleonea Bertholletia Cariniana Chytroma CorythophoraCorythophora Couratari Couroupita Eschweilera Gustavia Holopyxidium A. B. Foetidia Grias Lecythis TABLE

PLANCHONIOIDEAE FOETIDIOIDEAE NAPOLEONOIDEAE LECYTHIDIOIDEAE

TYPE TYPE MAIN MAIN

PLANCHONIA (syncolpate) LECYTHIS (colpate)

II.IL I. J. Muller: Pollen morphology Lecythidaceae 353

From this scheme it will be clear that Erdtman's assertion that a pollen morphological

line be drawn within the confirmed. demarcation can family can be However, before

this fact can be utilized for taxonomic subdivision it is necessary to evaluate the character

involved and whether other characters are correlated with to investigate any it. First of all, the fact that the difference between the Planchonia and the Lecythis main

is viz. be pollen types a qualitative one, syntricolpate versus tricolpate, must discussed.

While in none of the species transitions have been observed, this of course does not

imply that earlier in the phylogeny this has also not been the case. In fact, it is likely

that the syntricolpate condition has been gradually derived from the tricolpate one.

Evidence for this point of view can be found in recent observations on Passifloraceae

pollen by Presting (1965) and Pacque (oral communication) which show that varying and degrees of syncolpatism may occur, even within one species that, in that family at the condition is derived A second least, syncolpate a one. argument to consider the condition be based the fact that this characterizes the tricolpate as original can on type earliest Angiosperm pollen grains which occur in the early Cretaceous, while syncolpate later record the Planchonia types appear in the geological (Muller, 1970). Furthermore, other characters also. the and Lecythis main types differ in In the Lecythis type, grains are

the axis in the generally smaller, polar rarely exceeding 45// length, endoapertures are often more pronounced as in Eschweilera, Foetidia, Grias, and Napoleona, and the exine

is of than is in the Planchonia main generally a more simple structure found type, being thin less distinct typically composed of a endexine, a layer of more or columellae, and

a generally rather thin tectum which may be smooth (Bertholletia, Couroupita, Eschweilera, Holopyxidium), fmely reticulate ( Chytroma, Couratari, Grias, Lecythis, Napoleona), foveolate scabrate-verrucate (Foetidia), or (Crateranthus, Gustavia).

In contrast, the large (45 —60/u polar diameter) grains of the Planchonia main type lack defined while the generally a clearly endoaperture, syncolpate ektoapertures often show a number of specialized structures in the marginal zones. Especially striking in

the in The this respect are polar thickenings occurring the Barringtonia asiatica type. exine with structure on the mesocolpia may show a heavy tectum funnel-like depressions,

supported by columnate structures, comparable to the Tilia structure type described by and Godwin and Chambers (1961) Praglowski (1971). However, simple exine structures main is also occur in the Planchonia type and it especially the Barringtonia calyptrata type which be considered least evolved and which must as approaches certain representatives of the and the Lecythis main type especially pollen of Crateranthus. As can be seen on

Plate I, where the pollen of two representatives of the B. calyptrata type is compared to that of Crateranthus in both the columellae rather and congolensis, are conspicuous regu-

a medium almost smooth tectum larly distributed, supporting thick, (figs. 5, 6). An additional of is the of the striking point similarity presence scattered verrucae on aper- tural membranes This a feature which the Planchonia (figs. 4, 7, 8). is occurs frequently in main in main in type, but the Lecythis type so far only has been encountered Crateranthus pollen.

As already stated, the step from tricolpate (fig. 7) to syntricolpate (fig. 1), which is the differencebetween the of Crateranthus main pollen grains and the two representatives of the Barringtonia calyptrata type shown, although at present qualitatively definable, need

be construction not a fundamental one. Moreover, the general of the ektoapertures from endo- (apart the syncolpatism) and the absence of marginal grooves and of distinct

further The the apertures are points of agreement. highly complex pollen of Barringtonia asiatica is much less similar and side type probably represents a separately evolving branch in the phylogeny of the family. BLUMEA VOL. 354 XX, No. 2, 1972

In this connection it is of interest to review briefly the geographical distributionof the

pollen types. The Planchonia main type is restricted to the Old World tropics, ranging from and the The to west Pacific. Lecythis main pollen type is found the and The in American tropics, tropical Africa, Madagascar. genus Crateranthus is whilethe African, Barringtonia calyptrata type is restricted to New Guinea, North Australia, the Solomon and Caledonia. obvious that this distribution Islands, Fiji, New It is pattern

does not the idea that the latter could be related to support group closely Crateranthus,

unless assumes a relict distribution for one the B. calyptrata type.

On the other the transatlantic distributionof the main hand, Lecythis pollen type agrees well with the view that this be close the may to the ancestral pollen type of family. The of the Planchonia could then have been origin main type in Africa, presumably at a time

when transatlantic not more. this of migration was possible any In connection it is interest mentionthat the earliest which the to pollen grains can be assigned to B. asiatica type date

from the Paleocene of Borneo (Muller, 1970) and from the Eocene of India (Venkata-

& from chala Kar, 1968), while Payens (I.e., p. 172) cites fossil wood ofBarringtonia the

Eocene ofIndia. Puzzling in this context is a recent record of fossil Barringtonia leaves from

the Eocene of Alaska (Wolfe, 1972).

In it would that the main conclusion, appear two pollen types could be utilized, in combinationwith for subdivision macromorphological characters, a of the family, since

they probably reflect a Cretaceous split in the phylogeny, with one branch finding its

main development in South America and to a lesser extent in Africa, while the other branch has probably migrated eastwards from Africa, establishing a second centre of

diversification in the Indo-Pacific area.

TAXONOMIC SUBDIVISION

From the subdivisions ofLecythidaceae reviewed by Payens, it is only that of Niedenzu

which (1892) fully agrees with the pollen morphological evidence in the recognition of a Planchonioideae subfamily in which, as shown on the scheme showing the subdivision of

all the characterized the Planchonia main pollentypes, genera are grouped, by pollen type.

The other three subfamilies, Foetidioideae, Napoleonoideae, and Lecythidioideae are marked,

far known the main as as at present, by Lecythis pollen type.

Pichon's subdivision, dating from 1945, includes the genus Foetidia in a subfamily

Planchonioideae, although he has noticed a difference in pollen between Foetidia (smooth

and the other If check the pollen) genera (ornate pollen). we macromorphological characters utilized these authors for their it by two subdivisions, appears that the genera included Niedenzu by in Planchonioideae are characterized by the presence of petals, filaments which are more or less connate at the base, an undivided stigma, a placenta which is not peltate, and ovula in a vertical row, while Foetidia lacks petals, has the fila- ments free or nearly so, a divided stigma, and a peltate placenta with the ovules in a horizontal circle. Ifthe pollen character is added to this list it willbe clear that the demar-

cation line between the tribe Foetidieae and the rest of the Planchonioideae sensu Pichon is

deeper than between Planchonieae, Barringtonieae, and Combretodendreae. It is therefore

suggested that Foetidieae are restored to subfamily rank, as originally proposed by Nie- denzu.

AFFINITIES

The wider affinities ofLecythidaceae are more difficult to trace on pollen morphological evidence. Under the that the Planchonia the assumption syncolpate main pollen type is J. Muller: Pollen morphology Lecylhidaceae 355

would that the derived one, it appear tricolpate Lecythis type should be considered as basic close to the ancestral type. Essentially this is similar to the tricolpate-reticulate

and which dates back to the pollen type which is widespread among Angiosperms lowermost Cretaceous (Muller, 1970).

Of the families which have at various times been proposed as being closely related to

the Lecythidaceae, Myrtaceae are the most prominent in older literature (cf. Payens I.e., is in this in all p. 161) and it striking that family syncolpate grains dominate, although oblate unlike the Planchonia other respects these small, thinwalled, grains are syncolpate both type pollen grains. It is probable that syncolpatism has arisen independently in

Lecythidaceae and Myrtaceae and does not indicate close relationship.

Miers (1875) accepted affinities with Rhizophoraceae, which are characterized by small

tricolporate pollen grains with a tendency to equatorial fusion of the distinct endoaper-

which is similar the main tures, a type not to Lecythis type. Niedenzu (1892) also denies any relationship with Myrtaceae and suggests relationship with Rhizophoraceae and Sonneratiaceae. Pollen morphologically, however, there is not the slightest resemblance between Lecythidaceae and the latter family (cf. Muller, 1969).

Takhtajan (1959) retains Lecythidaceae in the Myrtales, postulating affinities to Sonnera-

tiaceae, Rhizophoraceae, and Myrtaceae.

affinities Cronquist (1968), finally, suggests to Malvales or, through common ancestry, possibly to Theales, denying at the same time any relationship with Myrtales. This, of

offers for since families to the former course, ample scope comparison many belonging

orders are characterized by tricolpate-reticulate pollen types.

In clear the conclusion, pollen morphology so far does not give any indication of affinities in the wider of Lecythidaceae, except a negative sense. However, Lecythis pollen studied detail and when this done clues be found. type has not yet been in is new may

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