Arisaema Quick Guide
Early to Flower: Intermedium, Kiushianum, Nepenthoides, Serratum, Serratum mayebarae, Sikokianum, Thunbergii urashima and Triphyllum.
Early Summer Flowering: Costatum, Fargesii, Ringens, Tortuosum.
Later to flower: Candidissimum, Consanguinem.
Arisaema can change sex multiple times during their lifespan.
Most require shade but some like/tolerate sun ie Consanguineum, Costatum.
Biggest danger is getting too wet before they develop foliage and sometimes later. You risk losing your prize plant. I have lost some this year, 2021, so please be very careful. Best to use a light and airy compost or add loads of sand or vermiculite. Once the foliage begins to fade cease all watering for pot plants. For ones in the ground make sure there is good drainage. I have A. Costatum that has been in the ground for many years with no issues.
Their Spathe/Inflorescence/Coloured bract come in a range of colours and all are streaked and most impressive. Nepenthoides is quite drab but Sikokianum is beyond impressive. All the others I have are amazing.
Most have an appendage to the Spathe of varying lengths. A. Intermedium also has a very long appendage to the Spadix. I measured one at over 80cm.
The rhizome/corm/bulb is actually a modified stem.
A. Flavum is the shortist 7 - 40cm and A. Tortuosum the tallest 180cm.