IT is like Spaghetti .. "I" ending is already plural the singular is
SpaghettO no S the same with Gnocchi (pl) 1 gnocco singular, Fetuccina
/pl: e and Serissa at plural ( many plants of serissa should be SerissE!
But the world goes like this

Theo

Patrick Alexander wrote:

Jim Lewis wrote:
Folks, I've shuddered and TRIED to bear it, but I can't any
longer.

THE PLURAL IS NOT -- HARDLY EVER (see below) -- INDICATED BY AN
APOSTROPHE! It is Serissas, NOT serissa's. It is web sites, not
web site's. It is bicycles, not bicycle's. It is bonsai not
bonsai's (bonsai is both singular and plural).

I don't know who started this style of spelling on the internet
(you seldom see it anywhere else - tho it is on at least one
billboard in Tallahassee!), but if I ever find him (or her)
he/she is toast!

It's generally heard this referred to as the `greengrocer's
apostrophe', in reference to signs advertising `potato's', `green bean's',
and the like. It's at least a pre-net thing... I'm sure you could learn
more than you ever wanted to know in the archives of alt.usage.english.
Also, one thing to add here--the singular of species is species. The
plural of species is species. `Specie' is not a word...

Patrick Alexander