We need all three statements of Shmuel:

From "the halachah follows R. Shimon Shezuri" we would think that he holds of Bilah;

From "there is no Bilah" alone we would think that he holds there to be no solution for this mixture of Kitniyos;

From these two statements alone there seems to be a contradiction in Shmuel, so we also need his statement that he follows the end of the growth process;

From "we follow the end of the growth process" alone we would think that this is also true for crops and olives, so we need his statement that he follows R. Shimon Shezuri i.e. only with Kitniyos.

Question: Why do we need his statement that "there is no Bilah"?

Answer: As the end of that statement tells us that there is Bilah for wine and oil.

(Beraisa): A Pasuk teaches us that Ma'aser follows the ingathering of grain and wine:

(R. Yosi haGelili): Just as grain and wine grow from the previous year's rain and have Ma'aser taken according to the previous year, so too for everything that grows from the previous year's rain.

This excludes vegetables, which grow from the present year's rains, and have Ma'aser taken according to this year.

(R. Akiva): Just as grain and wine grow from rainwater and have Ma'aser taken according to the previous year, so too for everything that grows from rainwater.

This excludes vegetables, which are also artificially irrigated, and have Ma'aser taken according to this year.

Question: What is the difference between these opinions?

Answer (R. Avahu): In a case where they are artificially irrigated, yet grow from the previous year's rains, as follows:

(Mishnah): Eunuch-onions and Egyptian beans which are sown as vegetables:

If water was withheld from them for thirty days before Rosh Hashanah, they have Ma'aser taken according to the previous year, and if the current year is Shemitah, they are permitted. (R. Akiva would disagree with this.)

Otherwise, they are forbidden if the year is Shemitah, and Ma'aser is taken according to this year.

Question: Why is Shevat the new year for trees?

Answer (R. Elazar citing R. Oshiya): Most of the rains have passed (and new growth begins), and most of the season is yet to come.

Question: Surely if most of the season is yet to come then it shouldn't be the new year yet!

Answer: It should be read as "even though most of the season is yet to come."

(Beraisa): R. Akiva once harvested an Esrog on the 1st of Shevat and took Ma'aser of two years (Ma'aser Sheni of the second year and Ma'aser Ani of the third).

(Tana Kama): This was because he followed both Beis Shamai (who hold that the 1st is the new year) and Beis Hillel (who follow the 15th).

(R. Yosi bar Yehudah): It was because he was following both R. Gamliel and R. Eliezer:

(R. Gamliel): An Esrog follows its sprouting, like a tree, for Orlah, Revai, and Shevi'is; it follows its harvesting, like a vegetable, for Ma'aser.

(R. Eliezer): An Esrog is like a tree for everything.

Question: How is it permitted to follow the stringencies of both opinions?

The halachah is ruled to always follow Beis Hillel.

(Previously): One may consistently follow either Beis Shamai or Beis Hillel.

Someone who follows the leniencies of both is wicked.

Someone who follows the stringencies of both is a fool.

Answer: R. Akiva wanted to follow Beis Hillel, but he didn't know if Beis Hillel followed the 1st or 15th.

Question: R. Yosi bar Yehudah is following Beis Shamai (as according to Beis Hillel, the sprouting and harvesting are in the same year)!?

Answer (R. Chanina or R. Chananyah): In this case the Esrog had sprouted before the 15th of the previous Shevat (and so according to Beis Hillel, the sprouting and harvesting are in different years).

The same would be true even if it was harvested before the 1st of Shevat; the story simply happened this way.

Alternate answer (Ravina): Emend R. Yosi to argue with the Tana Kama on two things:

It happened on the 15th of Shevat, not the 1st.

It was because he was following both R. Gamliel and R. Eliezer, not Beis Shamai and Beis Hillel.

(Rabah bar R. Huna): Since R. Gamliel ruled that Esrog follows its harvesting for Ma'aser (like vegetables), its new year begins in Tishrei.

Question: We see differently:

(Tosefta): If one harvested Esrogim both before and after sundown on the eve of the 15th of Shevat, Terumah and Ma'aser may not be taken from one lot to exempt the other.

If it was the third year entering the fourth, that of the third requires Ma'aser Rishon and Ani while that of the fourth requires Ma'aser Rishon and Sheni.

It is R. Gamliel who follows harvesting, and we see that the new year begins in Shevat!?