After spending some months in the neighbourhood of Madras, he was situated for more than two years at Mergui and collected extensively in Tenasserim. He was recalled to Calcutta in 1835 and attached to the Bengal Presidency in order to be sent with Dr Wallich and Mr M'Clelland to visit and inspect the localities in which tea grew wild in Assam. Griffith's full report on this enquiry led to the important economic conclusion (based largely on a critical comparison of the Assam flora with the flora of tea-growing regions of China) that tea might be successfully grown under the conditions in Assam and similar districts of India. When the other members of the expedition returned Griffith was detained in Assam, where he remained during the whole of 1836, making a successful expedition into the Mishmee mountains only once before visited by a European. Early in 1837 Griffith, accompanied by only one servant, set off on an exploring expedition through the very disturbed country of Burmah towards Rangoon. All news of him ceased, or rather his assassination was credited by the Government and reported in the newspapers, when in June he re-appeared, ragged and travel stained, in Calcutta. He had explored down the Hookhoom (Hokong) Valley and on to Ava, and had then proceeded more rapidly by river to Rangoon, conveying his collections with danger and difficulty. Appointed Surgeon to the embassy about to start for Bhutan, he filled up the intervening two months by again going to the Khasi hills to collect. He then accompanied the expedition to Bhutan, traversing over four hundred miles of the country and returning to Calcutta in June 1838. Here he spent the next few months arranging his collections and also studying the plants of the suburbs. In November he joined the army of the Indus and accompanied it in its whole march. He remained another year in Afghanistan making various expeditions in the country and into the Hindoo Koosh. He returned, after visiting Simla and the Nerbudda, to Calcutta in the middle of 1841. Griffith then proceeded to Malacca where he had been appointed Civil Assistant-Surgeon. He remained only a year, but long enough to appreciate the great interest of the district for his botanical work and to complete some important observations. He collected the plants of the province and also visited Mount Ophir. Recalled to Calcutta, he took charge of the Botanic Gardens and also lectured to the medical students during Wallich's absence from August 1842 to August 1844, pressing forward reforms in the gardens and using his opportunity for scientific observation. On Wallich's return Griffith remained for some months longer in Calcutta continuing his work, married in September, and returned to Malacca in December full of hopeful plans for scientific work there. He had barely arrived at Malacca and begun work than he was seized with a fatal illness and died on February 9, 1845.