Cunoniaceae

Primary tabs

Cunoniaceae

Description

Woody plants, from small shrubs to tall upper canopy trees, rarely hemi-epiphytes and stranglers, evergreen or rarely deciduous. Leaves opposite and decussate, or verticillate in alternate whorls, or rarely alternate (Davidsonia), pinnately or palmately compound (the latter outside Malesia), usually with a terminal leaflet, or trifoliolate, or simple/unifoliolate, the leaflet margins crenate-serrate or entire; In most genera of Cunoniaceae, interpetiolar (or interfoliar) stipules occupy a position between the areas of insertion of opposite or whorled leaves (Rutishauser & Dickison 1989). Where the leaves are opposite, each node of the stem typically bears two petioles and two stipules (one pair), and when the leaves are whorled, the number of stipules is usually the same as the number of leaves. These interpetiolar stipules are sometimes referred to as ‘fused’ but since each arises from a single primordium, i.e. is entire from its inception (Dickison & Rutishauser 1990), this terminology is somewhat confusing. The mature stipules may be triangular, ovate, lingulate, reniform, spoon-shaped with a narrow base, or bifid (Opocunonia), and the margin is usually entire or occasionally toothed. The stipules arise simultaneously with, or slightly later than, the accompanying leaf primordia and generally enclose the developing leaves of the same node and the terminal bud (Rutishauser & Dickison 1989). Stipules may be either caducous, usually leaving a distinctive scar between the petioles, or sometimes persistent, and they are often more persistent in juvenile foliage than in the adult. Colleters are often associated with the stipules and nodes, and in Ceratopetalum and Schizomeria they are adnate to the stipules to form glandular ribs over part of the adaxial surface (Rutishauser & Dickison 1989); their secretions often result in varnished buds and nodes, which are also apparent in some species of Eucryphia and in Anodopetalum (R.W. Barnes, pers. comm.).

While this general type of interpetiolar stipule is characteristic for the family there is some variation in the position and number of the primordia (Rutishauser & Dickison 1989). Intrapetiolar stipules (one pair per node) arise in the axils of the petioles of Geissois p.p. (western Pacific Islands), or occasionally four lateral stipular primordia coalesce to produce a pair of bifid mature stipules (Geissois p.p., Australia; Pseudoweinmannia, Australia). In Malesia and Australia, Gillbeea has four lateral stipular primordia at each node and they usually remain as independent structures at maturity (i.e. two pairs per node, see ) (Hoogland 1960; Dickison & Rutishauser 1990; Rozefelds & Pellow 2000). Each stipule is quite large and strongly asymmetrical with the side nearer the petiole the narrower one, and they are narrowly attached at the base; the venation is prominent, consisting of a distinct midrib and lateral veins (Hoogland 1960; Dickison & Rutishauser 1990). In the Caldcluvieae, there is one pair of interpetiolar stipules per node in Spiraeopsis, Opocunonia and Ackama, while in Caldcluvia s.s. there are two pairs of lateral, leafy stipules per node, as in Gillbeea (Rutishauser & Dickison 1989, pers. obs.).
Stipules present, mostly one pair of interpetiolar stipules per node between petiole bases (or the number of stipules equal to the number of leaves where the phyllotaxis is whorled), usually triangular-ovate or ± orbicular, sometimes bifurcate to deeply divided at apex, rarely intrapetiolar (outside Malesia), or 4 lateral stipules per node, foliaceous; usually caducous, leaving a scar in the form of a continuous arc between adjoining leaf bases (rarely, outside Malesia, arc interrupted). The structure of the inflorescence is quite variable. Inflorescences have been described in detail elsewhere for Weinmannia (Bradford 1998; Hopkins & Bradford 1998), Schizomeria (Hopkins in prep.), Cunonia (Hoogland et al. 1997) and Anodopetalum (Barnes & Rozefelds 2000).

The flowers are frequently pedicellate, the pedicels often articulating around the mid-point or towards the base, and sometimes widening gradually into the hypanthium. More or less sessile flowers occur in some species of Schizomeria, Spiraeopsis and Pullea, and small fascicles of flowers are found in some species of Spiraeopsis and most Malesian species of Weinmannia. Capitula and glomerules occur in Pullea. Axes within the inflorescence can be terete or ridged; they often bear indumentum, and lateral segments are often articulated at the nodes. Nodes typically bear bracts (subtending lateral axes and individual flowers or fascicles of flowers) and especially at lower nodes with opposite branching, they also bear ‘stipules’, i.e. a pair of opposite bracts in a lateral position at the node, between the insertions of the opposite axes, resembling stipules in shape and position but associated with reduced leaves or bracts and not with fully developed leaves.

The most common type of inflorescence, which is probably plesiomorphic in the family, is paniculate. In many cases there is a change in phyllotaxis from opposite and decussate branching at the lower nodes to alternate (spiral) at distal nodes, although the level at which this occurs within the inflorescence varies. The most distal, flower-bearing subunits are often cymose and this type of inflorescence is thus a thyrse in the terminology of Weberling (1989). Such inflorescences vary in shape from broadly triangular/paniculate to corymbose and in size from small (c. 5 cm across in Schizomeria gorumensis) to quite large (e.g. up to 50 by 30 cm in Spiraeopsis celebica). Their position (axillary, terminal etc.) is variable or fixed in different species. In Malesia, paniculate or corymbose inflorescences occur in all genera except Weinmannia.

According to Bradford & Barnes (2001), genera can be divided into two groups depending upon the timing of floral maturation. Within Malesia, ± synchronous maturation along the flower-bearing axes occurs in all genera except Aistopetalum, Ceratopetalum, Gillbeea and Schizomeria, in which the terminal flowers mature first (centrifugal maturation). In these latter genera, the distal subunits of the inflorescence are clearly cymes; in the genera with paniculate/corymbose inflorescences and ± synchronous floral maturation, the structure of the distal subunits is less clear.

In the following examples, typical inflorescence structures are described for the Malesian genera, but not all possible variations are included.
Inflorescences various; In Malesia, the calyx, corolla when present, androecium and disc usually show the same merosity as one another, typically 4-5 but varying from 3-7. The number of carpels forming the gynoecium is typically 2 but sometimes 3-8 in Malesia (and up to 14 or rarely 18 in Eucryphia; Bausch 1938; Dickison 1978).

The calyx arises from a hypanthium which varies from very short to cone- or cup-shaped. The calyx lobes are sometimes shortly connate at the base and they are often hirsute on the outer surface and/or hirsute on the inner one also. They are sometimes persistent, and sometimes enlarged in fruit (e.g. Ceratopetalum).

A corolla of free petals is uniformly present in some genera, absent in others, and variable in occurrence in Ceratopetalum. In Malesia, the petals are quite small, often membranous and rather inconspicuous, usually ovate, obovate or spathulate, sometimes ciliolate, and sometimes toothed (Schizomeria, Gillbeea), the teeth being glandular in Gillbeea.

The stamens are twice as many as the calyx lobes in all the Malesian species and inserted in a single series (see Dickison 1989, f. 4.1D). Outside Malesia, stamens may be equal to the number of calyx lobes (in some species of Weinmannia and Cunonia), few but irregular in number or numerous (in several genera including Geissois, Lamanonia, Pseudoweinmannia, Eucryphia, Bauera), described as complex polyandry by Ronse Decraene & Smets (1992), and sometimes inserted in more than a single series. The filaments are typically long, thin or sometimes fleshy, and subulate, usually shortly exserted beyond the perianth (occasionally far exserted, in some Geissois and some Cunonia, or included in Davidsonia). The anthers are small, the base is often incised and the apex rounded, emarginate or apiculate with an extended connective. The anthers of several genera of Cunoniaceae were illustrated by Endress & Stumpf (1991).

The disc is somewhat variable. Where it consists of free lobes, their number is usually equal to the number of filaments (e.g. Weinmannia in Malesia). Sometimes it is a continuous but deeply lobed ring, the indentations corresponding to the bases of the filaments. In these cases, the lobes are often paired and more united with the adjacent lobe on one side than on the other (e.g. in some Schizomeria and male flowers of Spiraeanthemum). If the incision between the lobes is not deep, the bases of the filaments are impressed. Entire or slightly indented toral discs occur in several genera, either as a fleshy, free ring (Gillbeea), as a fleshy ring, strongly adpressed to the gynoecium (Aistopetalum), or attached to the upper surface of the ovary (Ceratopetalum). In Lamanonia (South America), the disc is indistinct and visible only as a ring of darkened tissue at the base of the ovary.

The gynoecium is apocarpous in Acsmithia and Spiraeanthemum though the carpels are slightly adaxially connate at the base (Hoogland 1979, f. 2; Dickison 1989, f. 4.1C). In the Australian shrub Acrophyllum the carpels appear at least sometimes to be strongly adpressed rather than fused. In New Caledonia, the endemic genus Pancheria also has an apocarpous ovary.

Where the gynoecium is syncarpous, the carpels are united at the level of the ovary, and each carpel is surmounted by a free style or stylulus. In some genera with syncarpous ovaries, the number of carpels is clearly visible from suture lines on the ovary wall (e.g. Weinmannia); in others, the suture lines are not visible (e.g. Schizomeria). Semi-inferior ovaries occur in Ceratopetalum and Pullea, and in Schizomeria there is a slight tenden-cy towards a partially inferior ovary in some species. The styles are usually long, filiform and furrowed on the adaxial side or rarely short, thick and adpressed (Aistopetalum).

Stigmas are generally small and terminal, sometimes clavate (e.g. Acsmithia, Gillbeea, Spiraeanthemum, Weinmannia) and papillate, though there is variation in shape and distribution of papillae (illustrated in Dickison 1989). Outside Malesia, decurrent stigmas occur in Vesselowskya (Dickison 1989, f. 4.3E).

The ovules are typically bitegmic, crassinucellate and anatropous, though occasionally hemitropous or campylotropous (Cronquist 1981), usually apotropous but reported as epitropous in Acsmithia, Davidsonia, Eucryphia and Spiraeanthemum, as they are in Brunellia (Bange 1952; Cuatrecasas 1970; Cronquist 1981; Smith 1985; Dickison 1989). The embryology of Weinmannia fraxinea was described by Govil & Saxena (1976).
Flowers bisexual, sometimes distinctly protandrous, or unisexual in dioecious or polygamous plants, actinomorphic. Sepals 3-6(-9), usually 4 or 5, valvate or imbricate, in some genera enlarged in fruit, in others persistent or caducous. Petals alternisepalous, entire or deeply incised, and then rarely with terminal glands (Gillbeea), or ab-sent. Stamens usually twice as many as the calyx lobes, the alternipetalous ones often slightly longer than the alternisepalous ones, outside Malesia also ∞ or rarely equal to the number of calyx lobes or irregular in number; Ovary superior to half-inferior, 2-6(-14)-celled, syncarpous or occasionally apocarpous, each cell with its own style, styles often diverging and ending in a small inconspicuous stigma, or rarely stigmas decurrent. Ovules 1-, generally in 2 rows on axile or apical-axile placentas. Fruit dehiscent or not, usually small, fruit wall glabrous or hairy; Seeds 1-), fusiform to ellipsoid, smooth or papillate, rarely with elaiosomes (Pseudoweinmannia), in dehiscent fruits usually with wings at one or both ends or hairy without wings;

Distribution

Africa: Argentina: present Asia-Tropical:, Malaya (Peninsular Malaysiapresent); Thailand (Thailandpresent) Australasia: Chile: present Continental Africa: absent E Australia: present E Malesia: present Europe: absent New Caledonia: present North America: absent SW Pacific: present South Africa: present Southern America:, Paraguay (Paraguaypresent) continental Asia: absent southern hemisphere, extending into the tropics in Central America and the West Indies, Madagascar and the Mascarenes, the Pacific Islands, and throughout Malesia: present
About 300 species in about 26 genera, with c. 40 species in 10 genera in Malesia; mainly in the southern hemisphere, extending into the tropics in Central America and the West Indies, Madagascar and the Mascarenes, the Pacific Islands, and throughout Malesia; absent from North America, Europe, continental Asia (except Peninsular Malaysia and Thailand) andcontinental Africa except South Africa The family is most diverse in E Malesia, SW Pacific and E Australia and the only genera whose distributions lie exclusively outside this region are Platylophus (1 species, southern Africa), Lamanonia (5 species, Brazil, Paraguay, Argentina) and Caldcluvia (1 species, Chile, Argentina). There are endemic genera in New Caledonia (Codia, Pancheria) and Australia (Acrophyllum, Anodopetalum, Bauera, Callicoma, Davidsonia, Pseudoweinmannia, Vesselowskya).

Dispersal

— Morphology and anecdotal information suggest that anemochory is the dominant mode of dispersal in the family and there is a range of specialised structures (Dickison 1984, 1989).

In genera with dry, indehiscent fruits (Ceratopetalum, Gillbeea and Pullea in Malesia) the fruit is the unit of dispersal. In those with dehiscent fruits (Acsmithia, Opocunonia, Spiraeanthemum, Spiraeopsis and Weinmannia), the small, light seeds are the units of dispersal, whether winged (most genera) or hairy (Weinmannia). Besides the possibility of anemochory, exozoochory on the feet of birds has been proposed for the seeds of Weinmannia (see Florence 1982) and Cunonia capensis L. (Coates Palgrave 1970), but field observations appear to be lacking and there are no fleshy structures to attract birds to the fruits.

In Malesia, the indehiscent, fleshy, whitish or brownish drupes of Schizomeria are dispersed by bats, arboreal marsupials and birds, including terrestrial flightless cassowaries (Rumphius 1755, under Arbor vespertilionum; Pratt 1983; D. Wright, pers. comm.). I have found no data on dispersal in Aistopetalum, the only other genus in Malesia with drupes, although the fleshy, purple fruits of Davidsonia pruriens F. Muell. from Australia are eaten by cassowaries (Crome 1976; Stocker & Irvine 1983).

Outside Malesia, other mechanisms of dispersal have been reported. In Australia, the densely hairy, indehiscent fruits of Pseudoweinmannia are considered anemochorous and the seeds may be secondarily dispersed by ants since they have elaiosomes, while in South Africa the inflated, indehiscent fruits of Platylophus are probably dispersed by flowing water, as well as being consumed by pigs and birds (Coates Palgrave 1977; Dickison 1984).

Morphology

These notes apply primarily to the Malesian species unless otherwise indicated and expand characters given in the description of the family.

Our knowledge of the micromorphology and anatomy of the Cunoniaceae is due in large part to the work of W.C. Dickison† and collaborators, and in addition to papers on stipules, fruits and seeds, and wood anatomy cited below, he has dealt with vegetative characters (e.g. Dickison 1975a; Rao & Dickison 1985) and floral anatomy (Dickison 1975b). An overview of the anatomy of the family is provided by Gregory (1998).

Cytology

No counts are given for any Malesian taxa in the various indices of plant chromosome numbers. For taxa outside our region, 2n = 32 has been reported in several genera , 2n = 30 for Weinmannia racemosa L. f. and W. sylvicola Sol. ex A.Cunn. (Hair & Beuzenberg 1960) and Eucryphia lucida (Labill.) Baill. (Goldblatt 1976), and 2n = 24 for Pancheria sebertii Guillaumin (Hamel 1952). In the related Brunelliaceae, 2n = 28 occurs in Brunellia comocladiifolia Humb. & Bonpl., B. mexicana Standl. and B. sibundoya Cuatrec. (Ehrendorfer et al. 1984; Orozco 1991).

Notes

RDH started monographic work on Cunoniaceae while working for CSIRO in Canberra in the 1950s. His interest developed during numerous collecting expeditions with the Resources Survey to what became Papua New Guinea, where the family is relatively diverse. He published accounts for several genera, and his notes on others are deposited at the Laboratoire de Phanérogamie (P), Museum National d’Histoire Naturelle, Paris.

While based at the Rijksherbarium, Leiden in 1976-77, RDH prepared a manuscript for Flora Malesiana covering all the genera except Weinmannia and Schizomeria. HCFH revised Malesian Weinmannia at the Laboratoire de Phanérogamie, Paris in 1994-96 and Schizomeria at Lancaster University, U.K. in 1998-99. All species concepts and descriptions in the genera treated by RDH remain his although the generic limits have been altered slightly in line with recent phylogenetic studies. The introductory sections were written by HCFH where not otherwise attributed, incorporating notes by RDH and information published since 1977.

Citation

Hutch. - in Gen. Flow. Pl. Dicot. 1967: 4
A.C.Sm. - in Fl. Vit. Nova. 1985: 5
D.Don - in Edinburgh New Philos. J. 1830: 85
L.M. Perry - in J. Arnold Arbor. 1949: 139
Hufford & Dickison - in Syst. Bot. 1992: 181
J.C. Bradford & R.W. Barnes - in Syst. Bot. 2001: 354
Schltr. - in Bot. Jahrb. Syst. 1914: 139
Engl. - in Nat. Pflanzenfam., ed. 2. 1928: 229
Pamp. - in Ann. Bot. (Rome). 1905: 43