Cycas macrocarpa

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Figure 1. C. macrocarpa

Contents

Distribution & Habitat:

Rain forest ridges in southern Thailand and peninsular Malaysia.

Description:

A tall, attractive cycad to 12m tall, with glossy green leaves to 3.2m long. Leaves are noticably blue-green when immature.

Culture:

Warm, sheltered and moist, but well drained.

Figure 2. C. macrocarpa
Figure 3. C. macrocarpa immature seeds.

The Rediscovery of Cycas macrocarpa

A recent trip to Thailand gave an opportunity to study the cycads of that country in their habitats. This trip was greatly assisted br Mr. Kampon Tansacha, proprietor of the Nong Nooch Orchid Wonderland tourist village. Kampon is also a well known landscaper in Thailand, and a palm and cycad enthusiast.

It was during our visit to southern Thailand that one of our most interesting finds was made. We were taken by Mr. Poonsak Vatcharakorn, a plant and seed collector employed by the Nong Nooch village, to see a cycad growing around Sungai Padi near Sungai Kolok in the far south of the country. A very large and robust, tall cycad with very dark green, broad, sometimes undulating pinnae was seen in several village gardens in the district. We then saw several large remnant plants growing in old rubber plantations in the same area. The plantations had passed their productive life, and were being cleared for replanting. Unfortunately, the newer style of planting meant deep ploughing and removal of all vegetation, including the big old cycads. These cycads originally occurred in primary closed forest (rainforest), on well-drained, often sloping, deep sandy clay-loam soils, and are said to still occur on the less disturbed ridges in southern Thailand and northern Malaysia.

Figure 1. A large C. macrocarpa in an old rubber planatation.
Figure 2. C. macrcocarpa ex-Melesia, Durban Botanic Gardens.

After about half a day with these plants, we travelled to Narathiwat to contrast the Thai plants known as C. rumphii, still occurring naturally along the coast in that district. These were also robust plants with broad pinnae, but proved to be quite different in many other characters. A simple key below lists the differences.

  1. Cataphylls triangular, to 70 mm long, indumentum short,

grey to pale yellowbrown, closely appressed; new growth bright green; pinnae mid-green when mature, broad-based (5-8 mm wide at the base), with a broad, low, yellow midrib above: Cycas rumphii

  1. Cataphylls narrowly triangular, to 110 mm long,

indumentum thick and woolly, rusty red-brown; new growth distinctly blue; pinnae dark green when mature, narrow-based (2-4 mm wide at the base), with a narrow, raised, green midrib above: Cycas macrocarpa Although no seeds or sporophylls were seen on the forest species, an extensive search turned up two old seed-cases attached to seedlings about 3 or 4 years old. The seeds were large and of an unusual oblong shape, about 60 x 35 mm in size. They also showed no trace of the spongy endocarp so characteristic of the C. rumphii group, and clearly present in seeds of the plants at Narathiwat. Poonsak recalled visiting the Sungai Padi area some 4 years earlier, collecting seeds and taking photographs. On his return home after our trip to the south, he located the photographs, which showed a very distinctive megasporophyll shape and large, oblong seeds. These plants were clearly not Cycas rumphii, but what were they?

After my visit to Thailand, I continued on to England and spent some time in the herbarium of the Royal Botanic Gardens at Kew, trying to track down types for a number of old names. One specimen of note was No. 6361 from the East India Company herbarium, with a label reading 'Pakoo Galouwe/Cycas sp./Crew

near Tabong' and the words 'macrocarpa Griff. / Not. iv, p,

12' added later. The specimen in the main herbarium was of leaf portions only, but there was an old note on the sheet that stated 'fruit in mus.'. The 'fruit' were eventually tracked down in the Museum of Economic Botany, in another building 200 metres away. This proved to be seeds and sporophylls, and clearly matched the seeds from Thailand and Poonsak's photographs. The locality given is now known as Keru, in Melaka State, Malaysia.

This was also the specimen referred to in the description of Cycas macrocarpa by William Griffith (1810-1845), a British colonial physician with the East India Company, and later botanist and superintendent of the Calcutta Botanic Gardens. It also matches an illustration he made while at the Calcutta Botanic Gardens. He noted that the specimen was collected by Dutchman J.B. Westerhout, Assistant Resident of Malacca, in September 1842. Griffith did not publish his notes and drawings while living, and his work was bequeathed .t o the East India Company. It was compiled by John McLelland and published by the colonial govemment of Bengal in Calcutta in 1854. Although there was nothing to indicate that the illustration belonged to the description of C. macrocarpa, the compiler added a note to suggest that this may be the case, and it clearly matches the description and the specimen at Kew.

Although this publication was fully technically correct, it was ignored by all contemporaneous and subsequent cycad students. Foremost student of the Cycadales of that era, F.A.W. Miquel, overlooked the publication of the name C. macrocarpa until 1868, where he briefly mentioned it as a species unknown to him and doubtfully distinct. Alphonse de Candolle and his father collated, partly wrote and published a complete account of the known flora of the world over the period 1824-1876. He treated the cycads in 1856, including the name C. macrocarpa as a doubtful species, and noting that it was not known to him. In the Kew herbarium, the specimens collected by Westerhout were labelled C. rumphii and left there. Hooker and Jackson in 1893 placed C. macrocarpa into the synonymy of C. rumphii in 'Index Kewensis', a monumental publication endeavouring to list ALL published plant names and synonymies from the time of Linnaeus until 1885. There it has remained until now.

Although apparently fairly common in the ridge forests of southern Thailand and Peninsular Malaysia, C. macrocarpa has been rarely collected. Henry Ridley (Director of Singapore Botanic Gardens, 1901-1912) published the flora of the Malay Peninsula between 1922 and 1925, in which he noted 'hill forest forms of C. rumphii may be different'. Tem Smitinand later recognised the presence of 2 distinct taxa in southern Thailand in his treatment of Cycas for the Flora of Thailand. He correctly treated one as C. rumphii. but wrongly applied the name C. circinalis to the plants we now know to be C. macrocarpa.

A photograph in habitat was published in 'Nature Malaysiana' as Cycas sp.. Taman Negara (vol. 17, p- 47, 1992).

Figure 3. Plant in a rubber plantation with Poonsak

Although this species has been poorly known and collected, a few plants have turned up in odd places. Photographs sent by Roy Osborne of an unusual plant growing in the Durban Botanic Gardens in South Africa showed it to be C. macrocarpa. Some of the seeds collected by Poonsak made their way to the USA, and a few seedlings were recently seen in collections in Florida. This species is a beautiful and dramatic plant, and certainly deserves to be more widely grown.

References:

De Candolle, A. R (1868) Cycadaceae in Prodr. Syst. Nat. & Reg. Veg. 16(2): 522-548. Griffith, W. (1854a) lcones plantarum asiaticum 4 (Calcutta).
Griffith, W. (1854b) Notulae ad plantas asiaticas 4 (Calcutta).
Hooker, J.D. & Jackson, B.D. (1893) Index Kewensis (Oxford). Miquel, EA.W. (1868) Nouveaux materiaux pour servir a la connaissance des Cycadees. Arch Neerl. Sci. Exact. Nat. 3(5): 193-254, 403-425.
Ridley, H.A. (1925) Flora of the Malay Peninsula 5 (London). Smitinand, T. (1971) The genus Cycas Linn. (Cycadaceae) in Thailand. Nat. Hist. Bull. Siam Soc. 24: 163-175.

Contributed by:

Tan Chin Tong (Figure 1,2&3)

External Links:

Cycad Pages, IUCN, JSTOR, Trebrown

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