If there is any mention of "in lieu of flower, please give to..." I would NOT send flowers, even as a thought to the co-worker. Many people dislike the idea of using all those flowers (environmental concerns) and would much more appreciate the donation as a thought. A friend's brother died recently and although none of us knew his brother many made donations to the charities they identified (mainly environmental funds). Our friend was tremendously grateful. Flowers would have shown a nice "thought" but would have been completely against their values.

This being said, a card sent to the co-worker's home, signed by everyone in his close work environment if possible, would look like a good idea to me (but not another card upon the person's return).

So basically: I think you can have the card circulating in the office and send it, and wait for the obit for further instructions, like whether or not to send flowers, which should go directly to the funeral home (IMO).

Good luck...