Periwinkle offers a lovely little flower, but it is the leaves and the seeds that are used in folk medicine. The leaves and seeds are rich in the chemical vincamine, an alkaloid that has positive effects on memory and has long been used to combat the effects of aging.eriwinkle is used in folk medicine in the Philippines as a remedy for diabetes. Most of these practices are still followed. Rosy periwinkle grows up to two and a half feet tall. Leaves are oval and have a glossy surface.
C4 envelopes are 229 x 324 mm in size and a A4 card blank can fit inside or an A3 card blank folded in half. These C4 envelopes are ideal for sending A4 documents or certificates. C5 envelopes are 162 x 229 mm in size and fit an A5 card blank or A4 card blank folded in half.
If you use an A6 paper, which is actually an A4 paper that is folded twice, then the matching envelope format should be a C6 envelope. A C6 paper format should be matched with a B6 size envelope (125 mm x 176 mm) while a C5 paper should be matched with a B5 size envelope (176 mm x 250 mm). A C4 size paper should be matched with a B4 format envelope (250 mm x 353 mm). Finally, a B4 size paper should be matched with an E3 size envelope (280 mm x 400 mm). There is a different standard that is in use in North America. However, it should be noted that not all envelope sizes are used for sending mail.