Wairarapa archivist and gardening guru Gareth Winter said the plant was a hybrid derived from a rhododendron fragrantissimum (very fragrant) at the Cross Hills Rhododendron Gardens in Kimbolton, which is famous for its nursery and gardens bursting with the flowering woody plant.
Mr Winter said the Solway College plant originated at Gwavas Station in the Hawke's Bay, with cuttings taken and propagated at Cross Hills.
"It was a once popular, very scented rhododendron with white flowers with a pink tinge, almost apple blossom coloured with a heavy scent. But fragrantissimum is quite an untidy grower and this is an improvement on that."
Mr Winter said two plants were taken to the school and a place was set aside for a third Solway College rhododendron in Queen Elizabeth Park "at the back of the border and deliberately in close proximity to a camellia Kate Sheppard (the suffragist) - there's a couple only a few metres away".
He said the naming of the plants for the centennial was "a great idea for the college".
The opening ceremony of Solway College was held on February 8 in 1916 and the scene, according to a surviving photograph of the occasion, will be re-enacted in contemporary style at the centennial, said Mrs Siers.
Reminiscences from foundation pupils were also recorded such as that from Mina Laing, then of Riversdale, recalling that "we were dressed in pretty white party frocks and I remember well the hymns and the speeches".
Mrs Siers said the school will also host an "old fashioned bazaar" at the centennial, which had over many decades become an annual college reunion event - "but this will be with a twist and a touch of the contemporary market style".
The school community welcomes the public and stall-holders to the event on Saturday, February 6, she said, in keeping with the centennial maxim of "something for everyone".
To register for the celebration or as a stallholder ph Judy Siers on (04) 934 6334 or email judy.siers@millwood-heritage.com