Which 1970s Spider-Man cartoon had sentient alternate dimension plants?

Question

As a kid I have distinct memories of watching a Spider-Man cartoon on television. Given the house it was in, it could have been as late as 1981, but I'm pretty sure it was really the late 1970s.

I only remember two storylines from the cartoon (and I remember seeing them multiple times, which in hindsight, suggests that this was a budget production with limited material to pull from when broadcasting). One is Spider-Man somehow being transported to an alternate dimension where he fights and escapes from creatures that are essentially sentient plants. The plants - which I'm picturing as somewhat venus-flytrap-like - could move around and communicate and part of the story was Spider-Man prevented them from mounting an invasion of Earth. The plants basically ruled their own dimension and had built a temple where they try to sacrifice Spider-Man, or something like that.

The other one was simpler, it was an out-of-control boulder rolling through a city / suburbia, crushing cars like they're tin cans and doing other damage. In the opening and closing credits and in-between episode segments, it seemed like they used this one repeatedly as a sort of teaser thing (or possibly just to help fill the running time), but I'm pretty sure I saw the actual episode where Spider-Man stops the boulder to prevent more damage or injury.

Those memories are still very clear to me. Less clear is the main bad guy. I'm picturing him in a cloak with a hood; I am not sure if they brought Dr. Doom into that series, or if it was their particular incarnation of Green Goblin or somebody else. I remember the tone of the series being dark and scary, but that might just be from being a little kid. I don't remember any other superheroes ever showing up in the series.

I've tried to figure this one out several times over the years too. It turns out that the Wikipedia entry covering the various Spider-Man television cartoons over the decades is - as far as I can tell - very comprehensive. But going through it, and checking out some possibilities on YouTube and borrowing DVDs from friends, has yielded no matches.

Answer 1

Spider-Man 1967

This is certainly the series you're looking for, and the two episodes you describe are in fact two related episodes

Season 2 Episode 10: Vine

After inadvertently unleashing a giant plant on the city from a seed he found in the house of a missing scientist, Peter Parker travels back in time to 3,000,000 BC in order to find the professor himself. Spotting a great stone city in the distance, Peter quickly doffs his school clothes to reveal the costume of Spider-Man and, after a battle with an amphibious monster, is captured by a tribe of primitive blue giants. Taken prisoner to the city, Spidey discovers that the professor has become the benevolent ruler of giants and asks for help. The scientist reveals he destroyed the plans with radium. He explains that the only way to stop the menace is to steal radium gems from the temple of an evil society of intelligent plant monsters, which were mutated by its radiation and captured the city from its original inhabitants. Spider-Man is knocked out by the plants and put in an arena with 'Goliath', a giant caterpillar-like monster, for the amusement of the Master Vine. After a brief battle, Spider-Man webs up the beast, defeats the plant soldiers and takes the radium gems, which are the eyes of a huge statue. The plant civilization, dependent on the radiation for survival, withers away. Having returned the prehistoric city to its rightful owners, Spider-Man returns to the present and feeds the radium gems to the giant rampaging beast. Unable to absorb so much energy at once, it too withers away, saving the city once again.
_{List of Spider-Man 1967 Episodes}

While the video below shows the whole episode, it's linked to a scene where the Venus fly-trap like plants are seen:

(The video's have gone down, unfortunately)

Season 3 Episode 14: Rollarama

A remake of the second-season episode "Vine." When the city and its adjacent missile site are threatened by giant, rolling seed pods from another dimension, Peter Parker enters a mysterious portal to their point of origin to find a way to stop them. He is knocked out by a large creature and captured by a society of plant creatures. They reveal the world is becoming too cold for them. He finds himself the target of another society of intelligent plants, who are keeping the environment cool with a device powered by radium. He takes the radium, causing the plants to die, then uses the radium to destroy the rolling pods.
_{List of Spider-Man 1967 Episodes}

While the video below show the whole episode, it's linked to a scene with one of the rolling pods:

(The video's have gone down, unfortunately)