I'm looking for a website where I can discuss estoric questions about
ornamental plants, some place where I can ask knowledgeable people
about, for example, problems I'm having with a certain pest on some of
my hostas, sources for rare plants, or a plant that I am having
difficulty identifying.

Hello robbins~

There are several great forums for posting questions about gardening,
where experts and other knowledgeable folks (including Master
Gardeners) can answer them. Here are my favorites:

GARDEN FORUMS: This is a large site with a myriad of forums on
specific gardening topics, from propagation to pests, from roses to
cactus, from bog gardens to container gardens.
http://forums.gardenweb.com/forums/

FINE GARDENING FORUMS: Here you'll find a lot of experienced,
well-read gardeners, who can help with a wide-range of gardening
questions. http://forums.taunton.com/tp-overthefence

HGTV GARDENING FORUMS: This is one of my favorites. The folks here are
friendly, and there are many Master Gardeners hanging around. The
"General Gardening" forum allows you to post photos of those strange
bugs or diseases within your post.
http://boards.hgtv.com/6/ubb.x?a=cfrm&s=1084078532&f=9774011632


You might also enjoy these:

NATIONAL GARDENING ASSOCIATION BOARDS: http://www.garden.org/boards/

BETTER HOMES & GARDENS FORUMS:
http://www.bhg.com/bhg/category.jhtml;jsessionid=UPANKTLRDWKUFQFIBQSCAOQ?categoryid=/templatedata/bhg/category/data/Talk.xml

UBC BOTANICAL GARDEN FORUMS: http://www.ubcbotanicalgarden.org/forums/



Good luck!

Kriswrite

RESEARCH STRATEGY:
Researcher's personal knowledge and bookmarks

Thank you for your help!

quick comments:
HORT:
- UBC is good, though not busy. has photos.
- gardenweb is good, busy, but sometimes has logon problems (I've
never diagnosed the problem(s), but it hasn't been due to cookies or
scripts, AFAIK). has photos.
- usenet (nntp), though if new to usenet, you might want to learn to
filter trolls and flamers.
- forums.craigslist, which can be very local, though posts "age" very quickly.
 
Locale is very important, and you need to process info more carefully
when you are near mountain ranges or large bodies of water.

DESIGN:
for *landscape* or garden design, no good forum sites or newsgroups exist, AFAIK. 
Design ability (the "human"/psych/esthetic aspects) seems to originate
via upbringing or perhaps genetics. Many people are in the design
business; few are very good. (Likely due to displacement of designers
by the overwhelmingly asphyxiating necessity of marketing survival.)
For technical design questions, look for ag/hort, construction, or
engineering oriented info.
_____
Lotsa info is not on the net. 
Good info, though non-interactive: University libraries and textbooks
are good. Larger public libraries and community colleges libraries
often have a few "gems".
Old skool: local gardeners, groups. Specialized newsletters. *Your*
interest, observations, and experience. :-)