It comes with a pamphlet with interesting details on the stamps in 4 languages; Malay, Chinese, Tamil, English. But nothing is mentioned about the designer(s) of the stamps.
1¢ Arachnis "Maggie Oei", A Singapore-raised hybrid, cross made by Mr John Laycock in 1935 and raised in the Botanic Gardens, Singapore. "Maggie Oei" is a common orchid in local gardens.
8¢ Vanda "Tan Chay Yan", cross made in Singapore by Mr Tan Hoon Siang in 1949 and raised in the Botanic Gardens, Singapore. Mr Tan Hoon Siang names this hybrid after his father who was the first person in Malaya to plant Hevea brasiliensis (Para rubber) on an estate scale.
12¢ Grammatophyllum speciosum, largest of the Malayan orchid species, producing flowering stems to 2-3 yards long by 2 inches thick which bear a profusion of large reddy-brown flowers. Because of its colour, it has been called the "Tiger orchid".
30¢ Vanda "Miss Joaquim", the first Malayan orchid hybrid, being raised in 1893 in Singapore in the garden of Miss Agnes Joaquim. It is the commonest of orchid hybrids in Malayan gardens, and 40 years ago (which I supposed it is referring to 1923?) cuttings were sent to the Hawaiian Islands where it has become the most important plant of the orchid industry there.
50¢ Copsychus malabaricus, also known as "Shama", it is quite a common bird in Malaya but is seldom found in the open. The "Shama" is the finest song-bird in Malaya and its songs can be often heard from the gardens of houses in country districts. It is also kept as a cage-bird in Singapore and singing contests are often staged on Sunday mornings in some City coffee-shops (which I don't think it still happens today).
$1 Halcyon smyrnensis, this White-Breasted Kingfisher is the commonest Kingfisher in Malaya and is also a familiar garden bird. It generally keeps clear of the vicinity of water and feeds on large insects such as grasshoppers, lizards, frogs, nestling birds, in fact any living creature that it is able to catch and kill; it rarely eats fish. No nest is made, its eggs being laid in tunnels excavated in the bank of a stream or road.
$2 Leptocoma jugularis, this Yellow-Breasted Sunbird is probably the commonest Sunbird in the Malayan lowlands, especially near the coast, and is a frequent visitor to gardens. It probes into flowers in quest for nectar and insects with its long and slender tongue. It is particularly attracted to red flowers and is shown here on the stamp hovering before Russelia juncea. When it takes to flight, it invariably utters a shrill "chip, chip, chip" resembling the sound produced by the knocking of two pebbles.
$5 Haliaeetus leucogaster, this White Bellied Sea Eagle is a common bird and is found all round the coasts of Malaya and on the off-shore islands. It usually soars in circles at a great height and feeds on sea-snakes, fish and crabs. Crabs are dropped from a height on to rocks in order to break the shell.