Indoor Gardening

January is a perfect month to do a little indoor gardening, where it is warm and cozy and dry! With any luck, a little golden winter light streams through the windows.

Christmas cactus, paperwhite bulbs, and pothos vines enjoy extra light and warmth
(Warrior Girl, 3D art by Jason Quisenberry)

Your indoor plants may benefit from being moved around your home to a better location during the winter, either to avoid long periods of low, slanted sun or to capitalize on it. Spend some time observing where winter light lands and adjust plant placement accordingly. For example, plants that flourish in eastern or southern oriented windows in the summer may do better when moved to a western window in winter.

Pothos vines (Epipremnum aureum)

This is a good time to check over your indoor plants for pests, to re-pot or add soil, or to re-evaluate your fertilizer regimes. It's also a good time to learn more about houseplants that would thrive in your home environment, and maybe introduce a new specimen or two. You may want to try propagating plants from cuttings, or even force some bulbs out of season.

Forcing hyacinth bulbs

Indoor gardening doesn't have to be elaborate, but a few projects can provide a lot of satisfaction while you wait out the dark and damp days of winter, until spring comes with all its promise and chores.

Fiendishly Fertile

Most of the time when you cut into a grapefruit, you find a few seeds that you can easily flick away with the tip of your knife. I was surprised to cut into this grapefruit and see all of these seeds!

Seeds galore

Eager to get on with my breakfast, I didn't stop to count the seeds. But later wondered - how many seeds does a grapefruit produce? Was this an anomaly, or routine for some grapefruit varieties?

Turns out, some grapefruit (Citrus x. paradisi) can be seedless or nearly seedless, others may have up to 90 seeds! Learn more from Fruits of Warm Climates, by Julia F. Morton, the Rutaceae section: https://www.hort.purdue.edu/newcrop/morton/grapefruit.html. Although this grapefruit appears fiendishly fertile, it may only be about average!

Native Plant Propagation Workshop

I recently attended a native plant propagation workshop sponsored by Bring Back the Natives. After last year's focus on pollination and plant propagation, the workshop sounded like a good next step. Judy Addler teaches "California native plant propagation: How to create native plants from seeds, cuttings, and divisions". Judy is a passionate sustainable gardener and educator, with an experimental garden in Walnut Creek. She loves to teach kids and adults about native plants, biodiversity, ecology, and sustainable gardening.

Judy prepping for the workshop

Native seeds used for plant propagation

In the outdoor workshop, we learned about seed propagation, seed collection, and the importance of seed saving. We toured the dry garden that Judy has developed over the last 20 years, the teaching garden close to the nearby elementary school, and her personal test garden with its fruit trees, chickens, and water harvesting.

Dividing bunch grass for propagation

Native elderberry started from woody cuttings

Scions for edible walnuts may be grafted on to hardy native root stock

Judy demonstrated her approach to plant propagation – collecting seeds for later planting or just tossing them nearby the parent; dividing bunch grass and sticking the divisions in the ground; pinching off soft and hardwood cuttings for replanting; describing how English walnut scions were grafted onto native walnut root stock; layering native honeysuckle and grape vines; and sticking woody stems in the ground to sprout roots from the nodes.

Milkweed, favored by migrating Monarch butterflies, propagate through underground runners

Coyote bush (foreground) are dioecious so propagate with this in mind

Layering was used to start the native honeysuckle and grape vines on the fence

The whole-time Judy layers in information about observing the land, taking clues from nature, and using native plants to create a wildlife habitat. Her approach is fearless and experimental (not a root hormone or coddled plant in sight). We left with our collection bags full and ready to try it for ourselves. I highly recommend this workshop, and any other offered by Bring Back the Natives.

Ready to propagate plants collected in Walnut Creek

Sex in the Garden: Wrap Up

Understand the seed-to-seed life cycle of plants, learn how to clone plants through cuttings, division, and runners, and enjoy a few curiosities of the natural world.

Propagating succulents

Getting Started

Learn the basics about the life cycle of plants.

Sex in the Garden
Birds and Bees – Flower Parts
Birds and Bees – Pollinators
Birds and Bees – Fertilization
Birds and Bees – Seeds
Birds and Bees – Germination
Birds and Bees – Fruit Development

Plant Propagation

Increase your plant population by cloning what you have, using cuttings, runners, and division; and zoom in on a gallery of seeds from Alaska and California.

Plant Propagation – Cutting
Plant Propagation – Runners
Plant Propagation – Dividing
Seed Gallery (Alaska Ark)
Seed Gallery (California Ark)

What's Blooming?

Observe the natural bloom cycle of favorite Bay Area plants from January through June.

What's Blooming in January?
What's Blooming in February?
What's Blooming in March?
What's Blooming in April?
What's Blooming in May?
What's Blooming in June?

Curiosities

Enjoy several curiosities of the natural world.

Discriminating Squirrels
Zooming In
Twin Corn

Books

Learn more about how to grow and propagate plants.

Grow Your Own Plants

Seed Gallery (Alaska Ark)

I am taking advantage of my dad’s latest project of collecting seeds from all over the Western United States, by photographing some of the seeds using my Plugable Digital Microscope (a gift from my wonderful husband). Together we’re creating an informal ark of seeds and images!

Below is another gallery of seeds, this time collected from my folk’s garden in Southeast Alaska. As we’ve discussed before, gardening is tricky in Southeast Alaska because of the short growing season (albeit long summer days), and lots of rain, but my mom and dad have a beautiful garden every summer. See: Little House in Southeast Alaska, and Rainforest Gardening.

This time I scrapped the light table to illuminate the seeds from below, but am still experimenting with lighting and focusing techniques from above [compare with Seed Gallery (California Ark)]. These seeds are quite small, so I’m providing individual and group shots. Note that these seeds are not Alaska natives (although there is a native dandelion subspecies—ssp. ceratophorum). Still, the plants are hardy enough to survive the rigors of Southeast Alaska, so they are included in the Alaska ark!

Digitalis purpurea (Foxglove seeds and dried leaf bit; 1/4 inch grid)	Foxglove (group shot)
Leucanthemum x superba (Shasta Daisy seeds and dried flower bit)	Shasta Daisy (group shot)
Taraxicum officinale (Dandelion seeds and parachutes)	Dandelion (group shot)

HTML Tables

Seed Gallery (California Ark)

For the last year or so, my dad (the consummate naturalist and forester) has been working on a seed gathering project. Collecting seeds is a great idea, both for plant propagation in our gardens, and for preservation. Seed banks help preserve genetic diversity, provide a source for plant breeders, protect heritage plant varieties, and provide a seed source in case of natural disasters or war. In my dad’s case, I suspect he is just having pure, science fun!

Here is a gallery of some of the seeds collected throughout California. The pictures are taken with my Plugable Digital Microscope. I’m still working on techniques for using the tool to take botanical photos. In this case, I tried using a light table below the seed, but not sure it adds much (compare with Zooming In).

Pimpenella anisum (Anise)	Encelia farinose (Brittle Bush)
Washingtonia filifera (California Fan Palm)	Yucca brevifolia (Joshua Tree)
Marah macrocarpus (Wild Cucumber)	Unidentified - grass-like plant

HTML Tables

Plant Propagation – Dividing

A couple of months ago we changed our “Birds and Bees” series from sexual reproduction to asexual reproduction (see Plant Propagation– Cuttings, and Plant Propagation – Runners). We learned that asexual reproduction results in an offspring that is a genetic clone of its parent. Some plants produce offsets in the form of a new plant or bulbs.

Gardeners can benefit from these plant habits, by dividing a clump or digging up the bulbs, and replanting. Here are a couple of division projects I worked on this summer, using Jack Kraemer’s Grow Your Own Plants as my inspiration and guide.

Agapanthus spp. (Agapanthus)

I love Agapanthus. Our home came with a good collection of blue and white Agapanthus, and I have encouraged their growth all over the property. Some decry them as being common, and non-native. But I find them amazing and indestructible – thriving in both drought and monsoon.

Agapanthus originated in Southern Africa. They are monocots, and grow in clumps, sometimes even above soil. Periodically I dig up the clumps, and divide them by teasing apart their fleshy roots. They transplant easily to other garden beds, or to containers.

Agapanthus transplants

Agapanthus offsets ready to pull apart

HTML Tables

Crocosmia spp. (Crocosmia)

Our friends, Keith and Beth (both avid gardeners working their steep, terraced backyard) gave us some Crocosmia corms soon after we moved to the San Francisco Bay Area. Beth warned me that the plants are a bit invasive, so I planted them in a large container. Here in the Bay Area, the plants grow, flower, and die back twice a year. They bring a dash of orange color to the back patio when in bloom, and the long, strappy leaves catch the light in a beautiful way.

Crocosmia is native to the grasslands of Southern and Eastern Africa, from South Africa to Sudan. They are monocots, and grow from underground corms (often in chains, with the youngest corm on top and the oldest buried in the soil). The leaves have parallel veins, characteristic of monocots. Periodically I dig up the corms, thinning them out to give the remainder a little more room.

Crocosmia in a container

Crocosmia corms (and seeds)

HTML Tables

This brings our Plant Propagation series to an end for the year. We have barely scratched the surface of the topic, so look for more articles and projects in the future. In the meantime, I encourage you to look for ways to propagate your favorite plants. Redistribute the clones in your own garden, swap them with friends for genetic diversity, or give them away as gifts. You’ll save some money, spread some cheer, and participate in fun and practical science at the same time!

Plant Propagation – Runners

Last month we switched our “Birds and Bees” series from sexual reproduction, to asexual reproduction (see Plant Propagation – Cuttings). With asexual reproduction, a new plant forms as a genetic clone of a single parent. Asexual reproduction has some advantages if sexual reproduction is impossible, or if a grower wants to propagate multiple plants with the same characteristics as the parent plant. The disadvantage is that the plants may be vulnerable to some diseases, or pests.

In this article, I’m partnering with guest bloggers Al and Bina Harris from Southeast Alaska. They are reporting on their own experiences with stolons in their summer garden. Some plants send out runners (or stolons) as an asexual means of reproduction. A runner is a stem that develops at the crown of a plan and grows horizontally from the source. New plants form at nodes on the stolon, and take root while still attached to the parent plant. Gardeners can take advantage of this tendency, and plant the nodes to grow new plants.

Ranunculus repens (Creeping Buttercup)

The common buttercup is a fixture in damp meadows and drainage ditches in Southeast Alaska. They are lovely addition to the scenery when you are out hiking. If you are a gardener though, they are not as welcome. They send out many stolons which put down a new plant at each node. For the gardener, this represents the potential of a weed at every node!

Buttercup stolon - each node is a potential weed

Fragaria spp. (Strawberry)

The strawberry plant, on the other hand, sends out many stolons, which are welcomed by gardeners. Each node represents a potential strawberry plant to add to the strawberry bed!

A productive strawberry plant to the left, sends out a stolon to the right

Nodes guided to containers in which to take root

After several days the plants are doing fine and ready to be transplanted.
The originating stolon can be severed once the starter takes root.

The new plant is already sending out its own stolon

Seven of the ten new strawberry plants produced via stolon

Good healthy root systems in the new plants (and already producing more stolon)

Special thanks to Al and Bina Harris for photographs and report. It is always interesting to share stories with gardeners in other climates!

Plant Propagation – Cuttings

In our “Birds and Bees” series, we have been learning all about plant propagation. Up to now, we have been investigating sexual reproduction, which involves combining genetic contributions from both pollen (male) and an egg (female) to produce a seed. For the next few months we’re going to learn about asexual reproduction, where a new plant is formed from cells of a single parent (a genetic clone).

Asexual propagation can occur via leaves, stems, and roots. For the gardener, propagation methods include taking cuttings of a plant, dividing plants, separating stolons, harvesting bulbets or rhizomes, layering, and grafting. This summer, inspired by Jack Kraemer’s Grow Your Own Plants, I experimented with taking leaf and stem cuttings of some of my potted succulents.

Kalanchoe blossfeldiana (Flaming Katy)

The parent plant was part of a welcome gift from a new employer. Flaming Katy is a house plant, but mine has thrived outside in the mild San Francisco Bay Area climate for many years, surviving both drought and wet feet. In May, I stuck stems into regular potting soil, and three months later have rooted plants.

Top left: parent plant (and leaf cuttings). Top right: stem cuttings.

Bottom left: transplants. Bottom right: rooted stem cutting.

Schlumbergera truncata (Christmas Cactus)

I purchased the parent plant from the grocery store last year to help decorate the house for Christmas. Christmas Cactus is also a common house plant, but mine has thrived outside during our mild summer weather. The “leaves” are actually flattened stems, called cladodes. Each stem section sports several aerial roots. I stuck several of the stems into regular potting soil, and now have several new plants.

Top left: parent plant (still in its red foil wrapper). Top right: cladode with aerial roots.

Bottom left: transplants. Bottom right: roots.

Sedum morganianum (Donkey Tail)

The parent plant was a gift from relatives in Southern California. I was quite taken with their collection of potted Donkey Tails hanging from the trees and pergola in their  Huntington Beach backyard. I stuck individual leaves and stems into regular potting soil, and three months later have healthy, rooted plants.

Top left: parent plant. Top right: stems and leaves.

Bottom left: transplants. Bottom right: roots and a pup forming at the base.

Asexual propagation is a great survival mechanism for plants, especially when sexual reproduction is not possible. For the gardener, propagation using leaf or stem cuttings is a great way to propagate plants with desirable traits, and an easy way to multiply plants for your own use, or to give as gifts to friends and family.

Birds and Bees – Fruit Development

There is nothing better than summer fruit – nuts, peaches, nectarines, apricots, cantaloupe, watermelon, honeydew, berries, and more. They provide delicious nutrition and refreshment in the heat of summer, whether you eat them as is, whirled into a smoothie, or baked in a pie or crumble. Made into jam or jelly, or dried and preserved, you can enjoy the taste of summer in the cold, dark days of winter.

Fruit is the term used for a ripened ovary, typically from fertilized flowers (called true fruits). The term is also used for fruits that develop from other specialized cells in the ovule, other than the fertilized egg (called accessory fruits). Different fruit types develop related to the nature of the flower blossom (for a terminology refresher see: Birds and Bees – Flower Parts).

Fruit types, and their development.

Copyright @2008 Pearson Education, Inc. publishing as Pearson Benjamin Cummings

• Simple fruit (first column) – develops from a single carpel or fused carpel of a single ovary. Examples: nuts, beans, peas, tomato, orange, grape, melon, peach.
• Aggregate fruit (second column) – develops from more than one carpel, but all in the same flower. The mature carpels fuse together to form a single fruit. Examples: blackberries and raspberries.
• Multiple fruit (third column) – develops from an inflorescence or a cluster of flowers, which fuse together to form a single fruit. Examples: pineapple.
• Accessory fruit (fourth column) – does not develop from the ovary, but from another flower part such as the receptacle or hypanthium. Examples: strawberry, apples, pears.

The purpose of most fruit is to produce a seed. For some species the ovary develops into the fruit wall (the pericarp), and become soft and fleshy as the seed nears maturity (stone fruits, such as peaches). For other species, the pericarp becomes hard and dry (pea pods). Dry fruits may scatter from pods (poppy), or become very hard and retain their pericarps until they rot (acorns, almonds). When the fruit matures, it may be eaten, or remain in seed form until ready to germinate.

Learn More:

• Botany for Gardeners, by Brian Capon (Timber Press 2005). See Part V Reproduction, Chapter 9, “From Flowers to Fruits: Fruit Types”.
• Pollination and Fertilization, derived from Pollination and Fertilization, by Robert Bear and David Rintoul, for Open Stax, Rice University (Creative Commons).

Birds and Bees Seed Germination

A seed can lay dormant for months, years, or centuries (sometimes even longer), protected by its seed coat. It waits for the right environmental conditions needed to germinate. Germination refers to the beginning of growth, in this case from a seed. The ideal environmental conditions for germination include temperature, growing medium, and moisture.

Seed germination in monocots and dicots - © Merriam-Webster Inc. (2006)

Within the seed is the plant embryo—the immature plant. The embryo has all the characteristics of the plant it will become—root, stem, and leaves—in miniature. During germination the radicle, or root, emerges and pushes its way downward, using gravity, and grows and branches into the soil. The stem pushes upward, toward the light, and its cells grow and elongate. The germination process can be amazingly fast, taking place in a matter of hours, days, or weeks, depending on the seed type.

Dissecting a Joshua Tree seed (Yucca brevifolia)

Joshua Tree seed embryo (photos by Al Harris)

HTML Tables

The cotyledon, or seed leaves, emerge and provide nourishment for the seedling (the endosperm provides a food source in monocots). The seed leaves wither or drop off as the nourishment is consumed, until the first leaves emerge and begin photosynthesis. At that point the seedling is on its way to growing into a mature, self-sustaining plant.

Learn More:

• Botany for Gardeners, by Brian Capon (Timber Press 2005). See Part I Growth, Chapter 1, “Cells and Seeds: Basics and Beginnings”.
• Pollination and Fertilization, derived from Pollination and Fertilization, by Robert Bear and David Rintoul, for Open Stax, Rice University (Creative Commons).

Grow Your Own Plants

Grow Your Own Plants: from Seeds, Cuttings, Division, Layering, and Grafting is written by Jack Kramer, and illustrated by Michael Valdez. It was published by Charles Scribners’s Sons (New York, 1973). Jack Kramer is an American garden and plant expert who has written over a 100 books, and wrote a syndicated column for the Los Angeles Times for eight years. His books and articles cover a wide range of gardening and landscaping subjects. Other titles include Easy Care Guide to Houseplants, Cacti and Other Succulents, and The Complete Book of Patio Gardening.

The first chapter introduces the domain of sexual and asexual plant propagation, with a summary of key methods. Chapters two through four provide information about sowing seeds indoors and outdoors, and how to create the right environment of heat and light to start seeds. Chapters five and six are devoted to asexual propagation – different types of cuttings, layering, grafting, and others (division, runners, bulbs, and so forth). Chapter seven provides lists of trees and shrubs, perennials, annuals, and bulbs that are ideal candidates for asexual propagation. Chapters eight and nine cover house plant, vegetable, and herb propagation. Chapter ten describes hybridization, and gives a high-level summary of genes and genetics. The back matter includes a glossary, bibliography, and source of supplies (most of which are still current)!

I received my copy of Grow Your Own Plants in a box of gardening books from friend and fellow gardener, Charles (Chuck) Konigsberg (see Sunset Magazine Contributions to Western Gardening). It grabbed my attention, since one of my goals this year is to learn about plant propagation. I have been referring to the book to propagate plants, especially from cuttings. Even though the book is over 40 years old, it still stands up. The book is current, easy to understand, and full of practical information. The book reminds me of the “back to the land” movement of the 1970’s, and I love the line drawings by Michael Valdez. I recommend this book for your collection if you are interested in plant propagation.

Twin Corn

Here is a reproductive oddity – twin corn! This specimen came from my local grocery store, and piqued my curiosity about corn in general, and the phenomena of “twin ears” or “double ears”.

Twin corn - two ears of corn from a single shank.

Corn plants are monocots that grow a single stalk from 7 to 10 feet high, with multiple nodes. Leaves wrap around the stalk at the nodes. Corn plants are monoecious, with the male tassels growing at the top of the plant and producing pollen; and the female floral structure, or ears, growing at the nodes and providing the eggs. Corn silk attaches to each egg, or kernel, and pollination occurs when pollen falls on the silk. Corn, or maize, originated in the Americas, and is an example of ancient genetic engineering.

Roger W. Elmore and Lori J. Abendroth reported on multiple corn ears for Iowa State University in November 2006. Companies have been developing corn hybrids to produce multiple ears of corn per node (sometimes up to eight ears on a node). The extra ears are typically barren. In other instances, two ear shoots share a single shank on the same node. The second ear is typically much smaller with fewer kernels. According to the article, multiple ear shoots sharing the same shank is not unusual, but, in 2006, the number of “bouquets” of up to three to five ear shoots sharing the same shank increased significantly, and could not be explained. The concern was that the corn yield would be reduced by this oddity. They cited a report by R.L. (Bob) Nielsen from Purdue University about these “bouquets”.

In the end, I separated the twin ears, boiled them with the rest of the corn ears, and served them up with butter, salt, and pepper. The smaller twin was as flavorful as its sibling, but was smaller and with fewer kernels. Eating corn from the smaller ear reminded me of Tom Hanks, as Josh, eating the mini corn appetizer in Penny Marshall’s 1988 movie, Big!

Learn More:

• Plant & Soil Sciences eLibrary. “Anatomy and Reproduction of Corn”. Learn basic information about corn plants, and how they reproduce.
• Iowa State University, Agronomy Extension. “Multiple Ears Per Node: Iowa 2006 Situation & Hypothesis”. Roger W. Elmore and Lori J. Abendroth, Extension Corn Production, Iowa State University. November 2006. Learn about multiple corn ears per node, and per shank.
• Purdue University, Department of Agronomy. Corny News Network Articles, “A Problem with “Bouquets”. R.L. (Bob) Nielsen, September 12, 2016. Learn about the phenomena of corn “bouquets” from a single shank.

Birds and Bees – Seed Dispersal

Seeds dispersal refers to the transport of seeds from their plants of origin to new locations, where they can germinate and grow (or lie dormant until the right conditions exist). The seed shape and its characteristics help determine this locomotion, typically by wind, animals, water, bursting, or by humans.

Seed dispersal mechanisms - (C) Encyclopaedia Britannica (2006)

• Some seeds are equipped with parachutes, sails, wings, and propellers, and are carried on the wind. You might have blown on a dandelion to disperse its tiny parachutes, or seen a cottonwood tree release its seed fluffs.
• Animals play a part as well, by burying seeds, transporting burrs on their fur, or ingesting seeds, which pass through their digestive systems. (If you have been instructed to scarify a seed before planting, chances are in the wild the seed type must pass through an animal’s digestive system before it can germinate).
• Riparian plants may rely on water for pollination. Some seeds, like the coconut, are light enough to float to a favorable location.
• Some seeds burst out of their pod or container when the conditions are right (some actually need fire to be released).
• Humans also play their part, through planting crops, or transporting seeds from the nursery to their gardens.

I typically do not deadhead, because I love to see my plants go through their entire reproductive cycle, including producing seeds. I had once planned to remove a messy, and awkwardly placed black cherry tree in the back yard, until I witnessed a group of little brown birds devour its tiny cherries in an afternoon. How could I remove this food source, and dispersal system from our tiny ecosystem?

Learn More:

• Botany for Gardeners, by Brian Capon (Timber Press 2005). See Part V Reproduction, Chapter 9, “From Flowers to Fruits”.
• Pollination and Fertilization, derived from Pollination and Fertilization, by Robert Bear and David Rintoul, for Open Stax, Rice University (Creative Commons).

Birds and Bees – Seeds

This year we are learning more about plant propagation in a series called "Birds and Bees." In the last installment, our topic was the process of plant fertilization, which results in a seed that is comprised of the endosperm (nourishment for the seed), and an embryo (the immature plant within a seed). This time we are taking a closer look at seeds and seed parts.

Seeds can be distinguished between monocotyledons and dicotyledons (also called eudicots). Monocots are flowering plants that bear a single cotyledon  (one seed leaf), and usually have long, stalkless leaves with parallel veins (such as maize, grasses, lilies, and palms). Dicots are flowering plants that bear two cotyledons (two seed leaves), and usually have broad stalked leaves with netlike veins (like roses, daisies, beans, and oaks). Seed parts are similar for both categories, with slight variation.

Seed parts for beans (dicots) and corn (monocots)

As always, terminology is important for understanding seeds and seed parts.

Term	Description
Seed Coat	The protective coating around the seed.
Cotyledons	The food storage structure in seeds, and the first leaves that appear for seedlings.
Epicotyl	The region above the cotyledons.
Radicle (or Plumule)	The embryonic root.
Hypocotyl	The embryonic axis. This is the location between the root and where the cotyledons attach.
Endosperm	The food storage tissue in seeds.
Pericarp	The fruit wall in stone fruits, like peaches, pears, and apples. The pericarp is fused with the seed coating. (Not shown)
Miscellaneous	Monocot specialization: Coleorhiza – the sheath that envelops the radicle in monocots, such as grasses. Coleoptile – the protective sheath that covers the emerging shoot in monocots, such as grasses. Scutellum – the shield-like cotyledon of some monocots, such as barley and rice.

HTML Tables

Learn More:

• Botany for Gardeners, by Brian Capon (Timber Press 2005). See Part V Reproduction, Chapter 9, “From Flowers to Fruits”.
• Pollination and Fertilization, derived from Pollination and Fertilization, by Robert Bear and David Rintoul, for Open Stax, Rice University (Creative Commons).

Birds and Bees – Fertilization

This year we're exploring the fascinating world of plant reproduction in a series called "Birds and Bees." So far, we have mastered a few terms, and learned about the role pollinators play in bringing pollen and plants together. Now we're ready to enter the amazing events surrounding the fertilization of a flower's eggs.

Before fertilization can occur, each ovule within the ovary must be ready with a mature egg. When compatible pollen lands on the stigma, two cells within the pollen grain jump into action. One of the cells grows into a long pollen tube, through the cells of the pistil, in search of a microscopic opening in one of the ovules. If there are multiple ovules in the ovary, each ovule typically requires its own pollen tube.

Flower lifecycle – (C)2006 Merriam-Webster, Inc.

The second cell divides to become two sperm  cells that travel through the pollen tube to enter the ovule. One of the sperm unites with the egg in the ovule to form a zygote, the fertilized egg. The other sperm combines with another cell in the ovule to produce the endosperm, which is food storage tissue. The endosperm nourishes the zygote as it grows into an embryo, the immature plant within a seed. Amazing!