PALMS Moric i : Thr inqx in Cuba Volume 44(2) 2000

The GenusThrinsx inCuba

Canro MoRrcrPalmetum de Santa Cruz deTenerife, P arque Maritimo,3800L Canarias, Spainp alm e tum@b itm ail er. n et

1.. Thinax radi-a ta on l ime-stone rock, nearMaguana, Bara-coa.

Thrinsx palms, mostly T. radiata (Fig. 1) and Z mortisii, are the most common palms

of the Caribbean coasts. In contrast to these two ubiquitous species, the rest of the genus

is composed of unusual-looking palms, restricted to narrow habitats that are often

difficult to access. Some species are true pearls of the Antilles.

Soecies of Thrinax can at first be confused withCoccothrinax, but the former are easily recognizedby their white fruits, the smooth seeds (althougha few Coccothrinax bear smooth seeds) and thebases of the petioles that are split in the middle.

The genus Thinax, composed of seven species, ismuch smaller and by far better understood thanthe related genus Coccothrinax. All the species areeasily identifiable in the field and well

circumscribed taxonomically, but it is not clearhow they are related to one another.

Five species of Thrinax grow in Cuba. TWo of them,in the subgenus Thrinax, are widespreadthroughout the Caribbean; these are theubiquitous T. radiata and T morrisii mentionedabove. The rest of the native species are endemicto Cuba, are restricted to narrow habitats, andbelong to the subgeuts Hemithrinax.

PALMS 44(2): 63-68 6 3

PALMS Moric i : Thr inox in Cuba Volume 44(2) 2000

The only two species of Thrinax which do notoccur in Cuba are T. excelsa and T. pariflora, of thesubgenus Thrinax, and both are endemic ofJamaica.

Distribution and soil restrictions - Mogotes

AII Thrinax species in Cuba, except T. rivularis, arcrestricted to nutrient poor, calcareous soils. Thedistribution of these palms on the island seems tobe determined by soil type rather than by theclimate or habitat. All species, except T. rivularis,grow in sandy or rocky basic soils, often withlimestone. Thrinax rivularis grows in serpentinesoils, f i l led with heavy metals that jeopardizenutrient intake. All species grow at very lowelevations, mostly in coastal conditions. Thrinaxcompacta is an exception; it grows on the mogotesof the Altiplanicie de Nipe, at 450 m elevation.These populations thrive on the calcareous rocksdespite the habitat being much cooler and wetterthan those of the other species. Thrinax morrisiialso grows on mogotes in Viflales (Zona pers.comm.).

Mogote is the name used in Cuba for calcareoushills made of fossil coral rock. These limestoneoutcrops are usually dome-shaped and risestrikingly from a flat landscape. Their height isvariable, from the 20 m of those that host Zcompacta, to the 500 m of the famous mogotes ofViflales, home of T. morisii. The mogotes have awealth of vertical cliffs and are perforated bynumerous holes made by karstic erosion. The rockprovides little or no soil except some decomposingleaves trapped by trunks and rocks. This debris

3. ln Thrinaxcompacta theinfructescencesare unusua l lycompacr.

2. Mafestic leaf blades of Thrinax compacta can be morethan 2 m in overall diameter.

64

P A L M S Moric i : Thr inax in Cuba Volume 44(2) 2000

The Cuban endemic species

Thrinax compacta

This large species is endemic to the humidIimestone mogotes of south-western Sierra de Nipe,in southeastern Cuba. Its habitat is composed ofa low forest, with xeromorphic elements (Agave,Plumeria) and the palm Coccothrinax pauciramosa.Thrinax compacta is the only highland species ofthe genus in Cuba. Its habitat, at more than 400m a.s.l. is within a very moist highland area,known as Altiplanicie de Nipe. Rainfall is high(more than 25OO mmlyear), and the habitat ismuch cooler (mean annual temperature is around22"C) and wetter than any othet Thrina.x habitatin the lowlands, due to the usually cloudy, rainyand foggy weather. In fact, T. compacta is the mostmassive of the Cuban species. Leaves of adultplants have an average diameter of L90 cm (Fig.2) and recall in size and shape another highlandspecies, T. excelsa of Jamaica.

The specific epithet of this palm, " compacta," given'in 1883 by Grisebach and Wendland, recalls, Isuppose, the unusual shape of its inflorescences.These are not only much shorter than the leaves,

4. Thrinax ekmaniana, overlooking the lowlands.

can be substantial as in the habitat of T. compacta(up to 10 cm thick) or very thin (0-1 cm) as in themogote hosting T. ekmaniana. Most of the plantswhich grow on these hills are very specialized andendemic. The mogote species are: T. morrisii, T.ekmaniana and T compacta. Thrinax radiata canalso be found on coral rock in some localities.Thrinax morrisii also grows in the formacionesmogotiformes of northern Cuba. These hills are notdome-shaped and are formed by both coral rockand soil. They are a common sight in the landsaround La Habana.

The seedlings of the mogote species germinate insmall holes eroded in the limestone, that are ful1of rotting debris. These form l'natural pots" andthose that host seedlings are around 1L cm indiameter. As the plants grow, a mass of rootsexpands out of the hole. The size of this grotesqueball of roots can be up to 40 cm across, as observedin T. compacta.

ln the mogotes of Viflales, Thrinax monisii standsare more dense on the vertical external cliffs,probably because of the lack of competition fromother species and the increased availability of light.

5. Thrinax ekmaniana, with dry infructescences

55

PALMS Moric i : Thr inqx in Cuba Volume 44(2) 20OO

6. An unusual specimen of Thrinax ekmaniana that keepsmost of its drv leaves.

but are also extremely compact and spherical andbarely protrude out of the split base of theleafstalks which is virtually fiber free (Fig. 3). Therachillae are densely packed, curved and sinuousand the pedicels are very closely spaced (1-3 mm),so that when fruits are produced, they touch eachother forming a "ball" about 25 cm large. Such acompact structure in a forested and mesic habitatis unlikely to be wind pollinated. It may be beetle-pollinated. It is the only Antillean member of theThrinacinae to produce this kind of inflorescence.

Thrinax ekmaniana

This species is restricted to a few mogotes on thenorthern coast of Central Cuba covered by a lowopen scrub. The base of the hills is at 15 m a.s.l.,the tops of the different peaks are at 80 m to 180m. Thrinax ekmaniana (FiS. a) is the mostxeromorphic of all Thrinax species. The mogoteswhere it grows are, in fact, dry and fully exposed.The relatively low rainfall (1600 mm) isconcentrated in the rainy season (May-Oct) andthe palms survive during the remaining sixrnonths with only one fourth of the yearly rainfall.

It is interesting to note that the dry infructescencesof T. ekmaniana hang on the plant for at least ayear, keeping the dry fruits on them (Fig. 5).Thinax ekmaniqna is unique in this respect. Theunusal sheath fibers are pale, wirelike and floppy(Fig. 6).

In a recent issue of Palms (Morici 1999), Icompared this rock-spe cialist Thrinax species withthe most extreme rock-specialist Coccothrinax, C.munizii.

Thrinax rivularis var savannatam

Thrinax iralaris vaL savannarum (Fig. 7) is a small,compact and usually trunkless palm with shinybright green leaves with yellowish and silverytinges. The colorful brownish sheath fibers arejoined together, forming a dark sword shapedstructure. Also the white rounded fruits are visuallyattractive. It grows wild on the northern coast ofeastern Cuba in wet sandy savannah at lowelevations around the city of Moa. The rainfall ishigh (2000 mm/year) but the open vegetation iscomposed of small and tough-leaved savannah/scrub called charrascal, typical of the lowlands ofMoa. This Thrinax variety grows only in thesecharrascales and in virtually all of them. The areais characterized by "toxic soils" derived fromserpentine rock. The soil contains heavy metalsthat make plant growth difficult but host anexceptional flora with many endemic plants. Upto 3oo/o of the species are endemic to this area and70o/o to eastern Cuba in general (Borhidi 1991).The other palm species native but not endemic tothe charrascales of Moa arc Copemicia rigida, Bactriscubensis and a few species of Coccothrinax ofuncertain status.

Inflorescences of T, rivularis, up to 2 m long,project out of the crown of leaves. ln T. rivularisvaL savqnnarum, th.e rachillae are held well abovethe entire plant and are a striking sight in thesavanna. During sampling, I have noticed aconsiderable variation in fresh fruit size, rangingfrom 1 to 2 cm diameter.

Thrinax rivularis vaL savannarum is very abundantin the charrascales, in hilly coastal landscape.Marie-Victorin and Ldon (1942-1956) wrote thatthey could distinguish the shiny leaves of thesepalms in the vegetation while flying over Moa byplane and considered this palm one of the mostremarkable plants of the charrascales.

Thrinax rivulqris vat rivularis

This variety can be found in a relativelywidespread area around Moa that extendseastwards toward Baracoa, at least to Maguana. Itgrows within tall scrub or open forest. It is kept

6 6

PALMS Moric i : Thr inox in Cuba Volume 44(2) 2000

7. Thrinax rivu-Ioris var. sovon-norum growingin open chor-roscol on ser-pentine soil nearMoa.

separated from the other variety because itproduces a robust trunk that can be 6-8 m tall(Fig. 8), leaves are up to two times larger than theother variety and leaf stalks are longer than thesword-shaped leaf sheaths. Thus, the two varietieshave a distinct appearance, but it is disputablethat characters of this larger variety could becaused by overshading and shelter from thesurrounding vegetation.

Thrtnox in Cultivation

The subgenus Thinax has been extensively grormin gardens in the tropics. These palms are greatlyappreciated for their small size and tolerance ofdrought, poor soils, wind and sun. They showsome resistance to cold weather but theyapparently need warm and long summers tothrive. Thrinax radiata has been plantedsuccessfully in the Mediterranean climates ofsouthern Spain and southem Italy, where mafureplants can bloom and set ftuit (Morici & Puccio1998). Some specimens have been triedsuccessfully in the Canary Islands.

On the other hand, the subgenus Hemithrirnx isalmost unknown in culflvation apart from a fewbotanical gardens and it is totally absent from thenursery trade. For example, T. ekmaniana,according to the data of Botanical GardensConservation Intemational, was cultivated only atVentura College Community District, USA(fohnson 1996).

The Palmetum of Santa Cruz de Tenerife iscurrently growing all the species of the genus. Allthe Cuban species have been grown from wild-

collected seeds, vouchered with field data andherbarium specimens and are now about 4 yearsold. Seeds of different species have beendistributed to other botanical gardens.

None of the species suffered any special problems.I have noticed that species of the subgenusHemithrinax grow much more slowly than theothers. The slowest, Thrinax rivularis var.savannctrum, has been the slowest palm species ofthe 430 that have been cultivated at thePalmetum. Two years after sowing, plants hadproduced iust three or four leaves that were lessthan 14 cm long. Thrinax radiata of the same agehad produced 1O leaves and were more ttran 30 cmtall. This slowness is evidently due to its origin -

the "toxic" serpentine soils of Moa, charged withheavy metals. During my trips to Cuba I havecollected seeds of many plant species from Moaand they are always among the slowest growers oftheir genera. Most Moa plants have to invest effortin expressing their adaptations to this difficultenvironment, the most evident treing thethickness and rigidity of their leaves. Eophylls (thefirst leaf produced py a germinaflng seed) of Trtvularis vaL savannarum are the most rigid of allthe Caribbean Tfuinacinae that I have observed(18 species).

Seeds of T. ekmaniana are hard to germinate. Wehave observed much better results by keeping potsat cooler temperatures (15-20"C) during about 4months before warming up to the usual 3O"C.

Acknowledgments

TWo of my three visits to Cuba, between 1995 and1998, were fundedbythe Palmetum of Santa Cruz

67

P A L M S Moric i : Thr inqx in Cuba Volume 44(2) 2000

8. Taff pfants of Thrinax riyularis var. rivularis, nearMaguana, Baracoa.

de Tenerife. I am indebted to Manuel CaballeroRuano, director of the Palmetum project, whoprovided funding and help, both to organize thetrips and to make the plants grow. I express mygratitude to all the people who helped me in Cuba,especially the botanists Juan Hamacho and AnelMatos, Carlos P6rez Morales director of the"Centro de Extensi6n Agricola" of Santa Clara andthe people of the herbarium of Academy ofSciences in La Habana (HAC). I also thank myfri6nds Fabio Friscia andJavier Rodriguez Chirvez,who accompanied me during the expeditions.

Lrrtnarunn ClrEo

BonHror, A. 1997. Phytogeography and VegetationEcology of Cuba. Akad6miai Kiad6, Budapest,Hungary.

JoHNsoN, D. (m.) AND rHE IUCN/SSC Pamr SpEcrausrGnoup. 1996. Palms: Their con-servation andsustained utilization. Status survey and actionptan. IUC\ Gland, Switzerland and Cambridge,UK.

Manrn-VrcronrN, F.E.C. aNl p.E.C. LEoN. 1942-1956.Itin€raires botaniques dans l'ile de Cuba. Vol. I,il, II. Institut Botanique de Montreal , Canad6.

Monrcr, C. 1999. Coccothinax munizii. Palms 43:190-193.

Morucr, C. aNn P. Puccto. 1998. A brief account onthe cultivation of Thrinax and Gaussia insouthern Europe and the Canary Islands. ThePalm Journal I4O:32.

CTASSIFIEDSeed Service. Rare Palm Seed for the hobbyist or commercial grower. No order too small. please askfor my FREE catalog of Palm Seed. SEED SERVICE, INGE HOFFMAN, 695 Joaquin Ave., San Leandro,CA 94s77 USA. Tel/FAX (51o) 352-4291

RARE PALM SEEDS. Martin Gibbons & Tobias Spanner, the team that first U.o"ght yo" th" t""dr ofMedemia argun, Trachycarpus nanus and Nannorrhops ritchiana, now invite you tolend for their latestlist. Includes the recently rediscovered Arenga micrantha from 7000 feet up in Bhutan, very beautiful,very cold hardy. This time we think we can offer the mega-hardy green form of Nannorhop.s withconfidence! Chamaerops'cuifera', from the Moroccan Atlas Mountains, 6lue as Brahea armata. pleitocomiahimalayana from 6500 feet up the Himalayas, climbs to 80 feet, and frosted every year in habitat. Andthe cheapest Bismarckia seeds in town! These and many other rare introduciions, temperate andtropical, are on our new list. Bulk only. Web: rarepalmseeds.com. E-mail: seeds@palmcentre-.co.uk. Fax++49 89 1577902. Phones/addresses: see Roster. NEWI Collectors' small packet seed service available.

PERMANENT BOTANICAL GARDEN SIGNS FOR THE PRIVATE COLLECTOR. Call or write for brochure.Phone (760) 723-L354; Fax (760) 723-3220. Plant Signs (Gary Wood), 960 El Caminito, Fallbrook, CA9 2028. e-mail: palmnut@tfb. com Web page : http : //wr,r'w.plantsigns. com

5 8