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<div type="description"><p>Solitary or clustered, spiny, acaulescent, erect, or high-climbing, pleonanthic, dioecious, rattan palms. Stem eventually becoming bare, with short to long internodes, sucker shoots strictly axillary. Leaves pinnate, rarely bifid, sometimes with a terminal cirrus; sheath splitting in acaulescent species, in the exposed area usually densely armed with scattered or whorled spines, in one species (Calamus polystachys) the spines interlocking to form galleries occupied by ants, indumentum often abundant on sheath surface; ocrea often present, sometimes greatly elaborated, papery and disintegrating, or coriaceous, rarely greatly swollen or diverging with inrolled margins and occupied by ants; knee present in most climbing species; flagellum (climbing whip derived from a sterile inflorescence) often present in species lacking cirri, very rarely a small vestigial flagellum present in cirrate species (e.g., C. pogonacanthus); petiole absent or well developed, flattened adaxially, rounded abaxially, variously armed; rachis often armed with distant groups of reflexed grapnel spines; cirrus when present armed with scattered (rarely) or grouped reflexed spines; leaflets few to very numerous, single-fold, entire or in 1 species praemorse (C. caryotoides), linear to lanceolate or rhomboid, sometimes the terminal pair partially joined along their inner margins forming a terminal compound leaflet or flabellum, regularly arranged or irregular, grouped, sometimes fanned within the groups, concolourous or discolourous, variously bearing hairs, bristles, spines, and scales, midribs conspicuous or not, transverse veinlets conspicuous or obscure. Inflorescences axillary but adnate to the internode and leaf sheath of the following leaf, staminate and pistillate superficially similar, but the staminate usually branching to 3 orders and the pistillate to 2 orders, the inflorescence frequently flagelliform, very rarely rooting at its tip and producing a new vegetative shoot; peduncle absent or present, sometimes very long, erect or pendulous, variously armed; prophyll usually inconspicuous, 2-keeled, tubular, tightly sheathing, variously armed or unarmed, rarely inflated, papery or coriaceous, splitting down one side, usually empty; rachis bracts persistent, like the prophyll, close or sometimes very distant, variously armed, usually strictly tubular, even where splitting remaining tubular at the base, rarely irregularly tattering in the distal part, each subtending a first-order branch or ‘partial inflorescence’, this frequently adnate to the rachis above the bract axil, very rarely bursting through the bract; first-order branch bearing a 2-keeled, tubular prophyll and ± subdistichous, tubular bracts, unarmed or variously armed, each subtending a second-order branch, usually adnate to the first-order branch above the bract node; rachillae very varied within the genus, spreading to very short and crowded, bearing a basal, 2-keeled prophyll and conspicuous, usually distichous, tubular bracts with triangular tips, variously armed or unarmed, very rarely the bracts highly condensed and spiral, in staminate rachilla, each bract subtending a solitary staminate flower bearing a prophyllar bracteole, in pistillate rachilla each bract subtending a dyad of a sterile staminate and a fertile pistillate flower and 2, usually quite conspicuous, prophyllar bracteoles, very rarely each bract subtending a triad of 2 lateral pistillate flowers and a central sterile staminate flower. Staminate flowers symmetrical; calyx tubular at the base, 3-lobed distally; corolla usually exceeding the calyx, divided into 3, valvate lobes except at the tubular base; stamens 6 (12 in Calamus ornatus), borne at the mouth of the corolla tube, filaments often fleshy, elongate, sometimes abruptly narrowed, anthers medifixed, short to elongate, latrorse or introrse; pistillode minute to quite conspicuous. Pollen ellipsoidal, bi-symmetric; apertures equatorially disulcate; ectexine tectate or semi-tectate, psilate, perforate, coarsely perforate, foveolate, finely to coarsely reticulate, reticulate-rugulate, verrucate, gemmate or, rarely, ectexine intectate with large, loosely attached, psilate gemmae,aperture margins usually similar to surrounding ectexine; infratectumcolumellate; longest axis 17–67 µm; post-meiotic tetrads tetragonal[104/363]. Sterile staminate flowers like the fertile but with empty anthers.Pistillate flowers usually larger than the staminate; calyx tubular, shallowly3-lobed; corolla rarely exceeding the calyx, divided more deeply than thecalyx into 3 valvate lobes; staminodes 6, epipetalous, the filaments distinctor united into a short ring, anthers empty; gynoecium tricarpellate,triovulate, spherical to ellipsoidal, covered in reflexed scales, stigmas 3,apical, fleshy, reflexed, sometimes borne on a beak, locules incomplete,ovules basal, anatropous. Fruit usually 1-seeded, rarely consistently 2- or3-seeded, stigmatic remains apical; epicarp covered in neat vertical rowsof reflexed scales, mesocarp usually very thin at maturity, endocarp notdifferentiated. Seed with thick sweet, sour, or astringent sarcotesta, innerpart of the seed rounded, grooved, angled, or sharply winged, endospermhomogeneous or ruminate; embryo basal or lateral. Germination adjacent-ligular; eophyll bifid or pinnate. Cytology: 2n = 26.</p></div>
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<div type="fossil record"><p>Fossils attributed to Calamus include pinnate leaf fragments, spines and spine bundles, spiny bark, fruits, male and female flowers and pollen, but the leaf, spines and fruit could equally be attributed to other members of Calaminae or indeed to spiny members of Arecoideae. The oldest records of macro ‘organs’ are probably those from the Lower Eocene of southern England (Chandler 1957, 1962); under the cautionary name C. daemonorops, Chandler (1957) assigns spines, fruiting axes, young and older fruits, male flowers, one with disulcate pollen, and female flowers from the Oligocene flora of the Bovey Tracey Lake Basin, UK, and a pair of spines/prickles from the Lower Eocene Bagshot Beds (Chandler 1962). From the Landes District of France, Huard (1967) describes spines from Neogene lignite (“probably Miocene”), concluding that the closest comparison is with Calamus or Daemonorops. Other macro records include re-duplicate pinnate leaf fragments in association with a small “tessellated” fruit, C. noszkyi (Jablonszky 1914) from the Lower Miocene of Tarnóc, Hungary. From the upper brown coal seam of the Miocene Turów Basin, Poland, Czeczott and Juchniewicz (1980) describe fragments of spiny bark, epidermis and loose spine bundles, Spinophyllum daemonorops, which they conclude are probably from Calamus or Daemonorops. From the Miocene of the Czech Republic (Zittau Basin), Teodoridis (2003) also reports Calamus/Daemonorops-type spines. From the German Middle Miocene, Mai (1964), Mai and Walther (1978) and Gregor (1982) describe palm-like spine fragments, which they include in C. daemonorops. At least some of these fossil spine fragments could represent spiny members of tribe Cocoseae. Fossil records of palm-like equatorial disulcate (dicolpate) pollen are numerous; most are included in the fossil genus Dicolpopollis (Pflanzl 1956), but less frequently the names Disulcites or Dicolpites are used. The earliest record is probably that of Schrank (1994) who records Dicolpopollis from the Upper Cretaceous Yesomma Formation, northern Somalia. Van der Hammen (1954) records two species of Dicolpites from the Maastrichtian of Colombia, but the drawings of these grains do not readily compare with calamoid disulcate pollen and no suggestions regarding their possible affinity were made by the author. Two types of reticulate equatorial disulcate Dicolpopollis are described from the Palaeocene of Borneo (Muller 1968), and a verrucate pollen type is recorded from the Miocene of Borneo (Muller 1979). Dicolpopollis is widespread in Europe, for example: UK — Lower Tertiary, Woolwich, London Clay and Bagshot Beds (Khin Sein 1961, Gruas-Cavagnetto 1976); Austria — Lower Eocene, Krappfeld area (Hofmann and Zetter 2001, Zetter and Hofmann 2001); Czech Republic — Miocene, North Bohemian brown coal basin (Konzalová 1971); France — Lower Eocene, Paris Basin (Ollivier Pierre et al. 1987); Belgium — Lower Eocene, Argile de Merelbeke (Roche 1982). The Miocene sediments of the west coast of southern India are rich in Dicolpopollis, notably in Kerala State (Ramanujam 1987, Ramanujam and Rao 1977, Ramanujam et al. 1986, 1991b, 1992, 2001, Rao and Ramanujam 1975, 1978, Varma et al. 1986, Srisailam and Ramanujam 1982, Singh and Rao 1990) but there are also records from Maharashtra State, for example, Saxena and Misra (1990). Dicolpopollis also occurs in southeast India — Tamil Nadu (Sarma et al. 1984, Ramanujam et al. 1986, 2001); eastern India — Andhra Pradesh (Ramanujam et al. 1986, 2001); and in north eastern India — Shillong Plateau, Meghalaya (Salujha et al. 1973a, 1973b); it is also known from the Eocene of Burma (Potonié 1960). Dicolpopollis is abundant in the Eocene Nanggulan Formation of Central Java (Takahashi 1982, Harley and Morley 1995 — cf. Calamus paspalanthus), whereas D. metroxylonoides in the Tertiary sediments of Papua New Guinea (Khan 1976) is considered to have an affinity with Metroxylon. Dicolpopollis bungonensis from the Eocene of New South Wales, Australia, is favourably compared with the pollen of C. moti F.M. Bailey (Truswell and Owen 1988). Dicolpopollis is well known in some Tertiary deposits of China (Song et al. 1999). The first American record of Dicolpopollis (Tschudy 1973) occurs in the Eocene Wilcox Group, Mississippi Basin, southern USA where it is present in appreciable numbers (ca. 10% of sample) and has an “... apparently very short stratigraphic range making it a potentially very useful fossil.” The images in Tschudy (1973) are typical Dicolpopollis and can confidently be assumed to have a close affinity with Calamus. A review of the palaeopalynology and palaeoecology of Dicolpopollis is provided in Ediger et al. (1990). (N.B. The fossil genus Calamuspollenites should not be confused with Calamus; it is monosulcate and was placed in synonomy with Arecipites [= Arecaceae-like monosulcate pollen] by Nichols et al. [1973].) </p></div>
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