"Today was the first time he trained. Whether he can go 80 or not, I'm not sure. He's our most experienced lock. He's been the glue in that pack for a fair while. He's important. He's still keen, still enthusiastic and still loves playing for Ireland, so he's important.
"Today was his (Brian O'Driscoll's) first real training with the team as such. He went through all right so he looked good," added the New Zealand-born coach.
With Plumtree's appointment coming at the end of July, he has been limited to working with his new charges in a training camp and these two weeks leading up to the Samoa match. Despite the short time frame, he believes the Irish squad are focused and well prepared ahead of a big three weeks.
"I think we have maximised our time really nicely. We have been focused on also giving the players some downtime, some rest time to build that energy because obviously they have come from pretty hectic provincial schedules.
"We are trying to find that balance. You would always want more time. You always feel like you need more time and always like to do a bit more.
"That has been one of the things we have been concerned about, but in saying that this week has been really good because the intensity of the sessions has gone up. Trainings have been pretty physical.
"I think the players really enjoyed it. They have been pretty competitive. So, they get a bit of a break tomorrow and regroup Thursday to wrap it all up."
Ireland encountered some lineout issues in last season's Six Nations. Plumtree has already looked at strengthening the area, stating that in getting back to basics they would rid themselves of the errors made during the 2013 Championship.
"I've had a fair bit of time but not a lot of time in terms of that area (lineout), but I did have a look at some of those lineouts and quite often it's not about the lineouts - it's about an individual in the lineout, whether it's a poor lift, a poor jump or a poor throw that the lineout breaks down.
"It's just (about) trying to go back to the basics really and making sure everyone performs their role accurately in the lineout, so the lineout has a great opportunity to be successful.
"That is one of the keys. You forget at this level that you can forget about those basics. We have spent a lot of time talking about those basics and practising them.
"They already have their lineouts up their sleeves and a lot of experience, those guys, so they know what they want to do but it is making sure every time that every action becomes a habit and not a poor lift or a poor jump. That has probably been our main focus."
Ireland have lost once in five Tests against the Samoans, their 40-25 defeat coming at Lansdowne Road back in November 1996.
And Plumtree will be vigilant that complacency does not come into the equation against a side that has climbed to seventh in the IRB World Rankings, a place above Ireland.
The former South African Sevens international has been impressed with the work put in to change the fortunes of Samoan Test side as they look to build on last year's victories over Italy, Scotland and Wales.
"I think in the past Samoa relied on a lot of individuals but I was in South Africa when they were playing over there against Scotland, Italy and South Africa (last June) and they were playing as a team," he admitted.
"Defensively they were really well organised. They were training at my son's school so when I was going down to pick them up I was watching their training for a bit. I wasn't spying on them! I didn't realise this was going to happen.
"They were well organised, training was good and their work ethic was strong. They have really stepped up and I guess it is really because of the individuals they have playing around the world now, being exposed to different things, different teams and different environments and different cultures.
"They are a real threat now because they are not only dangerous because they are individually good. They play as a team."
As a former Natal Sharks head coach in Super Rugby, Plumtree knows a few of the Samoans who are likely to take to the pitch against Ireland this weekend, but with their development they have matched their strong pack with an equally impressive back-line.
"(Their out-half) Tusi Pisi was a real danger man in South Africa (on tour). He was really really dangerous from open play. He cut the Springboks up a couple of times and did the same to Italy and Scotland.
"(Alapati) Leiua on the right wing who plays for the Hurricanes, I know him from Super Rugby. He is an outstanding footballer and Kahn Fotuali'i is a good player at nine, dangerous as well. They have got their big carriers up front as well and guys that like playing with the ball offloading.
"They play Samoan rugby that suits them but the key for them - that has probably been the difference - has been the discipline they have shown in their structures, like defence.
"That has been a big emphasis for them and that is why they have improved a lot. They look well balanced. Their big forwards up front, they play over this part of the world as well, so you know they are going to be physical.
"They have some outstanding backs that play Super Rugby, so they are pretty experienced. They will be a genuine threat at the weekend, a good test."